At this size, SEO is an organisational problem.

Scale and ownership. Pages come from templates, so fixes multiply; sites have many authors, so quality has to be enforced by the system; and mistakes replicate instantly across thousands of URLs. The work shifts from optimising pages to optimising templates and processes.

By moving requirements into the publishing workflow rather than into a document. Required fields, validation before publish, and templates that produce correct markup by default. Training helps, but a guideline that depends on people remembering will fail at scale.

It is how much of your site a search engine will crawl in a given period. Below a few thousand URLs it rarely matters. Above that — especially with filters or parameters generating URLs — it matters a great deal, because crawling wasted on junk is crawling not spent on your commercial pages.

Redirects. Specifically, not mapping every old URL to a specific new one before launch. It is unglamorous work that takes real time on a large site, and skipping it is behind most of the dramatic traffic losses you read about.

For strategy, diagnosis, template work, migration planning and training — yes, and you get senior attention rather than a junior. For large-scale content production across many markets simultaneously, no, and I will tell you that at the first meeting rather than after signing.

Segmented, never as one number. Traffic and conversions by template and by section, because a site this size always has areas growing while others decline. A single aggregate line hides everything worth knowing.