The retainers we replace all look the same on paper. Monthly content calendar (looks fine). Quarterly audit (mostly cosmetic). Ranking dashboard (vanity). And one or two SEO apps installed years ago that the previous agency uses as their entire 'technical SEO' deliverable. Meanwhile the actual technical work that moves Shopify rankings (Liquid-level schema, collection canonical handling, app-stack pruning, faceted nav indexation control) sits untouched because the previous agency could not write Liquid.
Shopify-specific SEO knowledge does not transfer cleanly from generalist SEO. Shopify's default URL structure ships duplicate-URL patterns: a product can live at /products/handle and /collections/handle/products/handle. Robots and canonical configuration to handle that is not on by default in older themes. The Shopify sitemap auto-generates from the catalogue with no exclusion controls. Out-of-stock products generate soft-404 patterns that bleed crawl budget. None of this is fixed by an SEO app; it is fixed in the theme and at the URL configuration layer.
Done properly, Shopify SEO is one of the higher-leverage retainers a store can run, because the platform's defaults leave so much on the table that the first six months of work is mostly recovering ground the platform was quietly giving away. From month seven onwards the work is more conventional content and on-page, but the foundation lift is real and it compounds for years.