Website SEO: The Agency-Led On-Site Approach

For the wider context (how to choose, support models and objectives), start with our main article on a search engine marketing agency. Here, we focus on a more specialist question: how to choose an agency for website SEO when the top priority is to improve what already exists in depth (architecture, topic silos, internal linking), for both SEO and GEO.

Choosing a Website SEO Agency: Deep On-Site Optimisation (2026 Guide)

In 2026, the challenge is no longer simply to "do SEO", but to build robust on-site foundations that hold up over time, despite:

• the complexity of ranking signals (Google uses more than 200 ranking factors, according to HubSpot 2026);
• volatility (500 to 600 algorithm updates per year, according to SEO.com 2026);
• click concentration (the top 3 can capture up to 75% of clicks, according to SEO.com 2026; page 2 falls to 0.78% according to Ahrefs 2025).

In this context, an agency that specialises in website optimisation stands out through its ability to diagnose and change the system (site architecture, templates, internal linking, depth, consolidation) without introducing regressions. That is often the difference between marginal gains and a genuine step change in visibility.

Scope: On-Site Optimisation, Architecture and Internal Linking (SEO + GEO)

What an Organic SEO Agency Covers (and What We Exclude): Server-Side Technical SEO, Content Creation

In this article, we deliberately focus on on-site optimisation of an existing website, that is, what changes the site's ability to be crawled, understood, prioritised and distributed internally:

• auditing what exists before optimisation (real structure, depth, orphan pages, templates);
• restructuring the site architecture (categories, sub-categories, pillar pages);
• setting up and scaling internal linking (contextual, navigational, breadcrumbs);
• topic silos and facet management (without breaking the architecture);
• SEO risk management during a migration or redesign (redirects, canonicals, sitemaps, post-launch checks);
• local structural variants (local pages, local internal linking).

We deliberately exclude:

• server-side technical work (hosting, CDN, caching, infrastructure configuration);
• content creation (editorial production, writing, publishing calendar), which is covered elsewhere.

Why SEO + GEO Changes Website Architecture Priorities

SEO targets rankings on Google. GEO (Generative Engine Optimisation) targets being cited in generative answers (LLMs and AI Overviews). They converge on one key point: structure.

• In SEO, a clear architecture improves indexing and internal authority distribution (and therefore the potential to reach the top 10 or top 3).
• In GEO, explicit hierarchy and clear relationships between pages make extraction easier (definitions, evidence, reference pages, semantic links), increasing the likelihood of being cited.

Note: AI Overviews can reduce click-through rate even in position 1 (down to 2.6% according to Squid Impact 2025). That is why structural steering should also aim for "no-click" visibility via citations and mentions, alongside rankings.

Organic SEO Audit Before Restructuring: Diagnosing Your Existing Architecture

Audit, Optimisation and Prioritisation: Objectives, Constraints and KPIs

Before changing site architecture, a serious agency starts by defining:

• business objectives (leads, demo requests, quotes, sales) and the pages that drive those conversions;
• constraints (CMS, development capacity, release cycles, UX rules, legal obligations);
• KPIs (impressions, clicks, click-through rate, positions, indexed pages, conversions), with measurable before-and-after tracking.

An audit should lead to an executable roadmap, not an endless checklist. A useful method is to chain "observe → explain → decide": start from data (Search Console / Analytics), form testable hypotheses, then prioritise by impact, effort and regression risk.

To go deeper into the audit logic, see our dedicated article on the SEO & GEO audit.

Mapping the Real Architecture: Crawl, Depth, Levels and Orphan Pages

The "real" architecture often differs from the "theoretical" one shown in menus. An agency should produce an actionable view of:

• depth (clicks from the homepage) and strategic pages that are too deep;
• orphan pages (with no internal inbound links);
• clusters (groups of pages linking to each other) and isolated areas;
• templates that generate volume (filters, pagination, variations) and dilute crawl resources.

Google reminds us that page discovery happens "mostly" through links. In practice, an important page without strong internal links is discovered later, crawled less often, and tends to progress more slowly.

Analysing On-Site Performance With Google Search Console and Google Analytics

Without Google Search Console and Google Analytics, structural analysis remains incomplete. The goal is to connect structure to outcomes:

• Search Console: impressions, clicks, click-through rate and position by page and query, indexing, anomalies and near-top-10 opportunities;
• Analytics: engagement and conversions, to separate "visible but not profitable" pages from "profitable but under-exposed" pages.

On web performance, keep it pragmatic: aiming for 100/100 is not a business KPI. However, beyond 3 seconds, bounce probability increases by 32% (Google, 2017), and 40% to 50% of users leave a site if it loads too slowly (Google, 2025). An on-site-focused agency therefore prioritises high-stakes templates (mobile, revenue-driving pages) rather than cosmetic tweaks.

Spotting Cannibalisation, Duplication and Intent Conflicts Before Optimising

Before a restructure, an agency should identify:

• cannibalisation (multiple pages targeting the same intent), which confuses signals;
• duplication (near-identical variants, facets, near-duplicate content), which dilutes crawl and internal authority;
• intent conflicts (a category page behaving like an article, or vice versa), often visible through inconsistent Search Console queries.

The objective is not to delete blindly, but to decide: merge, consolidate, re-prioritise (parent page plus satellites), or redefine each page's role.

Qualifying Clusters: Semantic Coherence, Journeys and Content Architecture

A useful cluster is a set of pages that:

• answers a clear intent;
• is connected by explicit internal linking;
• naturally leads to value pages (contact, demo, quote, categories).

An architecture-led agency also checks journey coherence: a page that earns impressions should be able to pass users (and authority) towards a converting page, otherwise visibility grows without business impact.

Optimisation Methodology: Internal Linking, Architecture and Topic Silos

Restructuring a Website for SEO: Architecture, Pillar Pages, Categories and Sub-Categories

Restructuring site architecture means deciding where the "parent" information lives and how it branches. A robust approach:

• define level-1 pages (major categories or offers);
• create coherent levels 2 and 3 (sub-categories, segments, use cases) without multiplying weak pages;
• clarify templates (category vs sub-category vs pillar page) to avoid hard-to-interpret "hybrid" pages.

A useful benchmark: 70% of searches contain more than 3 words (SEO.com 2026). An architecture that enables more specific pages (without over-segmenting) captures long-tail demand better, provided internal linking makes them accessible and important.

Topic Silos: Definition, Model Choice and Implementation Steps

A silo is an organisation into coherent "blocks" where pages within the same theme strengthen each other through internal links, whilst limiting uncontrolled cross-links. The goal is twofold:

• improve Google's understanding of the topic (SEO);
• make information relationships explicit (GEO), helping generative systems summarise and cite accurately.

Typical steps:

1. define silos (themes, offers, intents);
2. identify the silo head (pillar page);
3. assign satellite pages and their roles;
4. implement vertical linking (pillar ⇄ satellites) and controlled horizontal linking (closely related satellites);
5. measure before and after (indexing, impressions, positions, conversions).

Intent-Based vs Offer-Based Silos: How to Decide

• Intent-based: useful when users seek answers or solutions before comparing suppliers (complex B2B, long cycles). You structure around problems and use cases.
• Offer-based: useful when the market is primarily organised by product or service categories (e-commerce, standardised services). You strengthen category and sub-category pages and their links.

Validate with Search Console: if queries and top pages cluster by "need" (intent), lean towards intent-based silos. If they cluster by "catalogue or offer", lean towards offer-based silos.

Facets and Filters: Keeping Navigation Useful Without Breaking Architecture

Facets can generate thousands of URLs and dilute crawling. A structure-focused agency aims for balance: keep navigation helpful for users without turning every combination into an indexable page.

• identify facets that create value (recurrent demand, conversion impact);
• keep a limited number of strategic faceted pages;
• avoid contradictory signals (inconsistent canonicals, multiple URLs for the same intent).

Internal Linking: Objectives, Rules and Common Mistakes

Internal linking helps you:

• guide crawling towards important pages;
• distribute internal authority (internal PageRank);
• make relationships explicit (topic → sub-topics → details), valuable for SEO and GEO;
• improve journeys (less friction, more conversions).

Common mistakes include:

• overly repetitive, uniform anchor text (low value, over-optimisation risk);
• sitewide links everywhere without hierarchy;
• revenue-driving pages more than 4 to 5 clicks from the homepage;
• strategic pages receiving few internal links from high-traffic pages.

Contextual Links, Navigation and Breadcrumbs: The Role of Each Layer

• Contextual internal links (within the body content): the most powerful for explaining relationships and pushing a target page.
• Navigation (menus): useful for global access, but should remain stable and prioritised.
• Breadcrumbs: an excellent hierarchy signal (category → sub-category → page), helpful for understanding and user experience.

Managing Internal Linking at Scale: Industrialise Without Losing Control

On a large site, the challenge is not "adding links" but maintaining a measurable, coherent system. A scalable approach works by templates and priorities:

• where to add link blocks (templates);
• which pages should receive the most authority (business-critical pages);
• which clusters to reinforce first (near-top-10 opportunities, pages already on page 2).

Prioritising Templates, Sitewide Links and Strategic Pages

You usually get more results by improving 2 or 3 templates that affect hundreds or thousands of URLs than by micro-optimising isolated pages. Effective prioritisation focuses on:

• high-traffic templates;
• templates hosting converting pages;
• templates that shape hierarchy (categories, hubs, listings).

Reducing Depth and Redistributing Internal PageRank

Two simple levers that are often highly cost-effective:

• reduce depth for strategic pages (more direct access from strong pages);
• limit areas that consume links without benefit (infinite lists, poorly controlled pagination) so internal authority flows towards value pages.

Action Plan for Optimising an Existing Website: From Quick Fixes to a Full Redesign

On-Site Quick Wins: Improve Clarity and Hierarchy (Without Touching Infrastructure)

• fix broken internal links and redirect chains that disrupt journeys and crawling;
• repair inconsistent breadcrumbs and navigation links;
• surface business-critical pages via links from high-traffic pages;
• clarify page hierarchy (roles, level, placement within the architecture).

Mid-Level Structural Optimisation: Merge, Split, Consolidate and Re-Prioritise

When an audit reveals cannibalisation or duplication, an agency may:

• merge competing pages into a single reference page;
• split a page that is too broad into a pillar page plus satellites;
• consolidate weak sections (low traffic, low usefulness) to reduce noise;
• re-prioritise by moving pages within the architecture to better reflect demand.

Major Workstreams: Architecture Redesign and Template Re-Definition

An architecture redesign becomes necessary when the site has accumulated structural debt:

• poorly defined or overly flat categories;
• templates that conflict (same information presented in inconsistent places);
• areas generating too many weak URLs (uncapped facets);
• user journeys not aligned with the intents that drive traffic.

Results can be striking when a redesign and SEO are managed together. A France Num case sheet (updated 09/03/2026) for an agency founded in 1998 cites examples where redesign plus SEO delivered gains such as +72% SEO traffic over 18 months and +332% more keywords in the top 10 (2021/2022 case), or +2,202% traffic after SEO support and a redesign (2015 case). These figures are not guarantees; they illustrate the potential impact of a well-executed structural programme.

SEO-Led Website Migration and Redesign: Protecting Traffic and Rankings

SEO Website Migration: Steps, Risks and Responsibilities

An SEO migration is not "just a redirects job". An agency should define:

• what is changing (URLs, templates, architecture, content, internal linking, tracking);
• responsibilities (who creates the mapping, who implements, who QA tests, who signs off);
• risks (loss of indexing, incorrect canonicals, broken internal links, missing strategic pages).

The operational principle is simple: do not lose signals (URLs, internal links, hierarchy coherence) whilst improving what needs improving.

Redesign Review: How to Avoid Traffic Loss During Major Change

An agency reduces risk by treating the redesign as an SEO project:

• inventorying pages that perform (Search Console);
• protecting high-value pages (traffic, conversions);
• rebuilding internal linking (not just copying menus);
• pre-launch QA and a post-deployment monitoring plan.

Migration Checklist: Redirects, Canonicals, Sitemaps and Post-Launch Checks

• Redirects: URL-to-URL mapping, avoid 301→301 chains, monitor 404s.
• Canonicals: verify they point to the right URLs (otherwise deindexing can happen).
• Sitemaps: include only canonical 200 URLs intended for indexing.
• Post-launch: URL inspection, monitoring excluded pages, tracking impressions, clicks and click-through rate.

Google indicates that, generally, publishing a site is enough for it to be discovered, but there is no guarantee of indexing. In practice, architecture and internal linking remain the most decisive levers for accelerating clean discovery.

Local SEO and Architecture: Structuring a Website for Location-Based Demand

Local Pages: When to Create, When to Consolidate, and How to Avoid Over-Segmentation

In 2026, 46% of Google searches have local intent (Webnyxt 2026) and 76% of users visit a business within 24 hours of a local search (Webnyxt 2026). Your architecture must capture this demand without creating hundreds of weak pages.

Good trade-offs:

• create local pages when there is real demand and a genuinely differentiated offer (area plus service);
• consolidate when information is identical (avoid near-duplicate pages);
• build a hierarchy (region → city → service) that remains easy to understand.

Local Internal Linking: Connecting Areas, Services and Relevance Signals

Local internal linking should connect:

• service pages ↔ covered-area pages;
• local pages ↔ proof pages (trust, practical information);
• local pages with each other only where the relationship is logical (proximity, same services).

The goal is to make geographic coverage explicit without burying the site under over-segmentation that is hard to maintain.

GEO (Generative Engine Optimisation): Structuring a Site to Be Cited by LLMs

Structural Signals That Help Generative Engines: Entities, Clarity, Hierarchy

To increase "citeability", generative engines need elements that are easy to extract:

• short, stable definitions;
• clear hierarchy (H2 and H3 tags, logical sections);
• explicit relationships between pages (contextual internal links);
• evidence and verifiable elements (data, methodology, scope).

Industry analyses suggest pages structured with H1-H2-H3 are more likely to be cited (State of AI Search 2025). Without slipping into superficial optimisation, this strengthens the case for clean architecture in service of understanding.

Reference Pages and Content Relationships: Organising Information Across the Site

A structural GEO strategy often involves:

• designating reference pages (hubs) that summarise and link to more specific pages;
• connecting related pages with contextual internal linking (not only via the menu);
• avoiding list pages with no context, which are less useful for citation.

Measuring GEO Impact Without Over-Interpreting Signals

Measuring GEO requires caution: fewer clicks do not necessarily mean less visibility (the "zero-click" effect). To stay reliable:

• track SEO trends (impressions, positions, click-through rate) and conversions (Analytics);
• test question scenarios (personas) and observe whether the brand is cited;
• document structural changes and outcomes without concluding from a single signal.

If you need a structured framework, the SEO & GEO audit module helps you prioritise objectively (pages, templates, signals) and track progress over time.

Budget, Timelines and Delivery: Agency Method and Reporting

How Long Does a Complete Website Optimisation Take?

For structural optimisation (audit → plan → execution → stabilisation), early effects are often visible in 4 to 6 months, with a more durable impact frequently built over up to 12 months, depending on competition, site history and size (2026 market benchmarks). A redesign or migration usually adds a project cycle (specification, development, QA, post-launch monitoring).

Key point: SEO consolidates signals (crawl, indexing, internal links, behaviour). Even strong structural decisions can take time to show in the SERPs.

How Much Does Full-Site SEO Cost?

Budgets mainly depend on site size and ambition. Useful benchmarks include:

• some agencies quote day rates around €500 for tailored support (2026 market benchmark);
• retainers can start around €900/month for a standard package (NOIISE), but one day per month is not always enough for large sites;
• a deep audit is often a separate workstream, ranging from roughly 1 week to 1 month depending on site size (market benchmark cited in our sources).

To connect spend to performance, the healthiest approach is to calculate SEO ROI (before and after, conversions, business value) rather than judging purely on a fixed fee.

Governance: Backlog, Sprints, Validation and Reporting

Serious on-site optimisation is managed like a project:

• backlog of tickets (affected pages and templates, acceptance criteria);
• prioritisation by impact, effort and risk, often delivered in sprints;
• QA (SEO regression checks, journeys, internal linking);
• regular reporting (Search Console and Analytics) and iteration.

This avoids a common trap: a one-off audit that becomes a backlog with no owner and no sign-off.

Going Further With a Structured Approach

When to Rely on an SEO & GEO Agency to Shape Architecture and Internal Linking

Working with an agency focused on website optimisation becomes relevant when:

• the site plateaus despite consistent effort (impressions and clicks stagnate in Search Console);
• architecture has become complex (facets, pagination, multiple templates);
• a redesign or migration is approaching (high risk of traffic loss);
• converting pages are under-exposed due to weak internal authority distribution.

What Incremys Helps You Scale On-Site (Without Unrealistic Promises)

Incremys is not an agency. However, the platform can help teams scale on-site steering (diagnosis → prioritisation → tracking), especially on high-volume websites. Based on user feedback, SEO teams use it to speed up prioritisation and incremental improvements to site architecture (notably in UX & SEO redesign contexts) and to track ranking changes more effectively.

For organisations that want to combine expertise with a clear operating framework, the Incremys SEO & GEO agency page outlines a tailored support approach (SEO, GEO and link building) — best considered if you want methodical coordination of workstreams rather than just a list of recommendations.

Finally, for predictive prioritisation (instead of working reactively), the predictive AI component can help estimate opportunities and organise execution, whilst keeping human control over decisions.

FAQ: On-Site Optimisation, Architecture, Silos and Internal Linking

How do you carry out an organic SEO audit before optimising a website?

Start by cross-referencing three signal families:

• Search Console (indexing, queries and pages, click-through rate, positions);
• Analytics (converting pages, engagement, device segments);
• structure mapping (depth, orphan pages, clusters, templates).

Then translate findings into decisions: what to fix, where, in what order, and how to validate (before-and-after KPIs).

How do you optimise a website after auditing what already exists?

Prioritise by impact, effort and risk:

• quick wins (internal links to business pages, hierarchy corrections);
• consolidation (merge and split, noise reduction);
• major work (architecture redesign, template re-definition).

Validate each iteration using Search Console (impressions, click-through rate and positions) and Analytics (conversions).

How do you restructure a website for SEO without losing pages that already perform?

First, inventory the pages driving the most traffic and conversions. Preserve their role (or improve it), keep URL continuity where possible, and rebuild internal linking to protect authority distribution. Pre-launch QA and post-launch checks are essential.

What are topic silos in SEO and how do you build them?

A topic silo groups pages within the same theme around a pillar page, connected through coherent internal linking. To build them: define the themes, choose a silo head page, assign satellite pages, then implement vertical linking (pillar ⇄ satellites) and controlled horizontal linking.

What is internal linking and why is it important?

Internal linking is the set of links between pages on the same site. It helps Google discover and understand your pages, and it redistributes internal authority towards strategic pages. For GEO, it makes information relationships explicit, supporting comprehension and citation.

How do you successfully manage internal linking at scale?

Work by templates rather than URL by URL: identify high-traffic templates, add useful and controlled link blocks, reduce depth for business pages, and measure the effect across URL groups in Search Console.

Can internal linking replace link building?

No. Internal linking optimises what you already have (authority distribution, crawling, hierarchy). Link building adds external authority. In practice, internal linking can unlock a new level (especially if architecture is weak), but it does not replace external signals in highly competitive SERPs.

How do you manage a website migration and redesign from an SEO perspective without a traffic drop?

Prepare a redirect mapping, validate canonicals and sitemaps, rebuild internal linking, and complete thorough QA before launch. After going live, monitor indexing, exclusions, impressions and clicks in Search Console.

How long does a complete website optimisation take?

Allow around 4 to 6 months for early effects, and up to 12 months for durable consolidation, depending on site size, competition, history and the scope of changes (especially with a redesign).

How much does full-site SEO cost?

It varies by size, objectives and complexity. Market benchmarks mention day rates around €500 for tailored work and retainers starting at roughly €900/month for standard packages, but a "full site" scope often requires more operational capacity and governance.