Common mistakes in large-scale site migration - Brighton SEO Oct 2026 - Rebecca Yu

Talk: Common mistakes in large-scale site migration
Speaker: Rebecca Yu - SEO Manager in JAKALA

At enterprise scale, a migration isn’t just an SEO project – it’s a web development project involving dev, UX, content and analytics teams. The talk walks through six structural failure points:
      1.    Not knowing where you are – understanding the operational landscape: project timelines and dependencies, Agile vs waterfall, working in Jira (epics down to acceptance criteria), and the traps between staging and pre-production environments.
      2.    Not knowing your source of truth – how a single page is built from CMS, DAM and PIM, and why you need to map each data point before planning things like schema at scale.
      3.    Not knowing your boundaries – separating SEO problems from dev, content or governance problems, using an LCP example and a RACI matrix to clarify who owns what.
      4.    No MVP for SEO tests – defining must-haves for launch and rolling out new SEO features in phases: proof of concept, pilot, then full release.
      5.    Confusing human errors with system errors – telling apart a manually set value that wasn’t updated from flawed automation logic, with canonical and schema examples.
      6.    Not factoring in scalability and new trends – planning URL structures that leave room for new markets, and preparing sites for AI agents and agentic browsing.
Key takeaway: migrations succeed or fail on organisational understanding as much as technical SEO – know the landscape, your data sources and your role, and build in room to grow.
Possible Q&A angles: how to get SEO tickets prioritised, working with devs on ownership, and what “agent-ready” means for sites today.

Transcript

1. Common mistakes in large-scale site migration Rebecca Yu JAKALA @Linkedin: rebecca-yu
2. About the Speaker • Hong Kong → newsroom → SEO • Travel, media, SaaS, ecommerce • Technical & international SEO rebecca-yu
3. What is a Large-scale Site Migration
4. The Difference Between Large-scale and Others Large scale site Medium Site Small Site 100,000+ URLs 1,000 - 10,000 URLs 100 URLs Cottage rebecca-yu Building Housing Estate
5. What it is Like to Work in Large-scale Migration Large scale site Imagine a large scale site migration is like moving a whole housing estate from Brighton to San Diego Housing Estate rebecca-yu
6. The 6 Structural Failure Points in Large-scale Migrations 1 4 Not Knowing Where you Are No MVP for SEO Tests rebecca-yu 2 5 Not Knowing Your Source of Truth Human Errors vs System Errors 3 6 Not Knowing Your Boundaries Not Factoring in Scalability / New Trend
7. 1 Not Knowing Where you Are
8. Mistake #1: Not Knowing Where You Are What is the Operational Landscape? • • • • Timeline (When): When is the hard launch date, and more importantly, when is the code freeze? Way of Working (How): Are we shipping this via Agile sprints or a rigid Waterfall roadmap? Where does the work live? If your SEO requirements aren’t written as clear, actionable tickets in Jira, ClickUp, or Notion, they do not exist. Stakeholders (Who): Who actually has the authority to sign off on your technical risks? The Environment (Where): What is the correct environment to work on rebecca-yu
9. Mistake #1: Not Knowing Where You Are Timeline rebecca-yu
10. Mistake #1: Not Knowing Where You Are Timeline : When is the hard launch date, and more importantly, when is the code freeze? 2026 rebecca-yu
11. Mistake #1: Not Knowing Where You Are Timeline Folder Finalisation (Business & Content) Site Architecture Redirection Planing Timeline Dependencies Page Templates (UX Team) rebecca-yu Source of Information i.e. CMS / DTS (Dev) Schema mapping
12. Mistake #1: Not Knowing Where You Are Way of working (WoW) rebecca-yu Agile Waterfall Repeating cycles Linear and strictly sequential steps.
13. Mistake #1: Not Knowing Where You Are Way of working (WoW) Ticketing Hierarchy Epic The Big Initiatives - Your whole | migration workstream └─ Feature A phase of the workstream └─ User Story ──┐ SEO requirement └─ Tech Story ──┴─ Implementation work behind user stories └─ Acceptance Criteria Your QA Conditions rebecca-yu
14. Mistake #1: Not Knowing Where You Are Way of working (WoW) Ticketing Hierarchy Epic Core Web Vitals └─ Feature Cumulative Layout Shift └─ User Story ──┐ When Mobile visitors landing on Homepage, avoid page | elements shifts when page loads └─ Tech Story ──┴─ Defer the promo pop-up injection until after first user interaction (scroll, tap, or 5s dwell — whichever first) └─ Acceptance Criteria CLS score < 0.1 on mobile (Field data via CrUX/PSI, real-user data — not just lab) rebecca-yu
15. Mistake #1: Not Knowing Where You Are Who - There are different ways to optimise image size, which route should we take? Task: To Optimise Image Size rebecca-yu
16. Mistake #1: Not Knowing Where You Are Who - There are different ways to optimise image size, which route should we take? Task: To Optimise Image Size Manually Adjust Content Manager Digital Asset Management Platform Engineer Content Delivery Network Infras / DevOps #Acceptance Criteria rebecca-yu #RACI
17. Mistake #1: Not Knowing Where You Are The environment Staging Site Pre-production Site Canary Live Site A private clone of the website used by developers and QA teams to test code changes and content updates securely before any public release. A final, production identical environment containing a full replica of live data where SEOs, content managers, and business stakeholders perform final user acceptance testing (UAT) before launch. A live, isolated server instance used by engineering teams to route a tiny percentage (e.g., 1-5%) of real user and search engine traffic to a new site version to monitor for real-world bugs or server crashes before a full rollout. The public-facing, indexable website infrastructure used by your actual customers, users, and search engine crawlers to interact with your brand in real-time. rebecca-yu
18. 2 Not Knowing Your Source of Truth
19. Mistake #2 - Not Knowing the Source of Information Guess how many platforms are used to generate a page like this? rebecca-yu
20. Mistake #2 - Not Knowing the Source of Information CMS CMS - Page level SEO copy, meta tags rebecca-yu
21. Mistake #2 - Not Knowing the Source of Information CMS DAM CMS - Page level SEO copy, meta tags DAM - Product Image DAM rebecca-yu
22. Mistake #2 - Not Knowing the Source of Information CMS DAM CMS - Page level SEO copy, meta tags DAM - Product Image PIM PIM - SKU, price, stock DAM PIM rebecca-yu Further Read: Customer-first product categorization https://www.wix.com/seo/learn/resource/customer-first-product -categorization
23. Mistake #2 - Not Knowing the Source of Information Structured Data - Understanding each field where’s the source of info. rebecca-yu
24. 3 Not Knowing Your Boundaries
25. Mistake #3 - Not Knowing Your Boundaries Who’s Problem rebecca-yu
26. Mistake #3 - Not Knowing Your Boundaries DEV problem or SEO problem rebecca-yu
27. Mistake #3 - Not Knowing Your Boundaries Page rebecca-yu
28. Mistake #3 - Not Knowing Your Boundaries Responsible Accountable Consulted Informed
29. Mistake #3 - Not Knowing Your Boundaries Responsible Accountable Consulted Informed RACI: Optimising LCP in Migration - Tasks SE O De v QA PM 1. Diagnose LCP element per-template (e.g. ≤2.5s) R C C A 2. Optimise LCP assets (hero img, video poster, font) C R I A 3. Implement preload + fetchpriority for the LCP resource C R I I 4. Improve server response time / TTFB (CDN, caching etc.) I R I A 5. Remove render-blocking CSS/JS above the fold C R C I 6. QA & validate LCP against target — pre-launch gate C C R A
30. Mistake #3 - Not Knowing Your Boundaries The role of SEO is to evidence the issue and convince relevant parties it is a problem worth fixing. rebecca-yu
31. 4 No MVP for SEO Tests
32. Mistake #4 - No MVP Version of SEO features Minimum Viable Product (MVP) On-page SEO MVP - Canonical Tag Robot directives Meta Tags Clean URLs Targeted Keywords Image Size Alt text Can come later - Schema … rebecca-yu
33. Mistake #4 - No MVP Version of SEO features Rolling out a new feature 1 2 3 MVP / Proof of Concept (POC) Pilot Testing Full Scale Production An internal test to check feasibility rebecca-yu A controlled, small-scale rollout A sitewide release
34. Mistake #4 - No MVP Version of SEO features Rolling out a new feature >> Applying Product Schema to PDPs 1 2 3 MVP / Proof of Concept (POC) Pilot Testing Full Scale Production PDPs page samples from selected categories rebecca-yu Implement to a full category PDPs (Men’s Shoes) Release to all categories PDPs Further Read: Implementation of Schema via GTM https://www.linkedin.com/posts/radustoian_implementation-of-schemas-via-gtm-br ightonseo-activity-7247698547729428481-SjtC
35. 5 Human Errors vs System Errors
36. Mistake #5 - Messing up Human Errors vs System Errors Human Error System Error An SEO issue caused by a manually-set value that wasn't updated when the underlying system or content changed An SEO issue caused by automated platform logic producing incorrect or inconsistent output at scale, because the underlying rule wasn't built to account for a specific edge case or exception. rebecca-yu
37. Mistake #5 - Messing up Human Errors vs System Errors Human Error System Error Manual canonical input field Parameter-Blind Self-Referencing Canonical Page URL: https://www.example.com/new-url-path Page URL: https://www.example.com/product?utm_source= newsletter ❌<link rel="canonical" href="https://www.example.com/old-url-pa th"> (field was manually overridden) ✅<link rel="canonical" href="https://www.example.com/new-url-p ath"> rebecca-yu ❌ <link rel="canonical" href="https://www.example.com/product?utm_s ource=newsletter"> ✅ <link rel="canonical" href="https://www.example.com/product">
38. Mistake #5 - Messing up Human Errors vs System Errors System Errors Example - Schema Schema: AggregateOffer ✅ priceCurrency: GBP ❌ lowPrice is entirely absent — a critical/required field for AggregateOffer. rebecca-yu
39. 6 Not Factoring in Scalability / New Trend
40. Mistake #6 - Not Factoring in Scalability / New Trend Launch Day Planned Market Expansion? International URL structure in place? rebecca-yu AI Shopping Assistant WebMCP / UCP?
41. Mistake #6 - Not Factoring in Scalability / New Trend Does the current structure reserve space for scaling? rebecca-yu
42. Mistake #6 - Not Factoring in Scalability / New Trend Agentic Browsing llms.txt WebMCP - https://developer.chrome.com/docs/ai/webmcp UCP - https://developers.google.com/merchant/ucp rebecca-yu
43. The 6 Important Points in Large-scale Migrations 1 4 Organisation Landscape Timeline, stakeholders, way of working, environments SEO Tests Phases MVP, Pilot Test, Full Rollout rebecca-yu 2 5 Source of Truth CMS, DAM, PIMs, Algolia, ElasticSearch Human vs System Errors Canonicals, Schema and more 3 6 Boundaries What belongs to SEO and what does not? Future Growth Market Expansions, Agentic Shopping
44. Thank You rebecca-yu