Most programmatic SEO fails for one reason: the pages are empty templates with the keyword swapped in. Search engines and readers both see straight through them, and you end up with a thousand pages and no traffic.
The ones that actually rank do the opposite. Each page answers one real question a person actually types, and it puts a real answer on the page: a number, a comparison, a specific fact that is genuinely useful whether or not the reader ever buys anything.
The part people skip is the filter. You need a check that looks at each generated page and kills it if it has nothing to say. Publishing a page that cannot answer its own question is worse than not publishing it, because it drags down everything around it.
So the recipe is boring and it works: one page, one question, something true and specific on it, and a gate that refuses the empties. Scale is the easy part once each page earns its place.