Most sites lose their search visibility long before anyone writes a meta description. The damage happens earlier — in the URL structure, the rendering strategy and the content model agreed in week one.
Architecture is the ranking factor nobody audits
URL structure, canonical strategy and internal linking are decided when the sitemap is drawn. Change them after launch and you are trading link equity for a redirect map.
A useful habit: before design starts, write out every template the site will need and the single canonical URL pattern for each one. If two templates can produce the same content at two addresses, fix it on paper.
Rendering decides what crawlers actually see
A page that only assembles itself after three client-side requests is a page a crawler may index empty. Server-render the content that matters and hydrate the rest.
This is not an argument against interactivity. It is an argument for deciding, per template, which content is part of the document and which is an enhancement.
Content models outlive campaigns
Seasonal pages come and go. The structure underneath them should not. Keep the permanent taxonomy stable and let campaign layers sit on top of it.
When the structure is stable, a redesign becomes a presentation change rather than a migration.