Google’s John Mueller answered a question the question of how long it takes for SEO to work and what it means if rankings don’t change after a year. Sometimes best practices doesn’t work and John Mueller explains why this sometimes is the case.
https://www.searchenginejournal.com/google-says-best-practices-can-have-minimal-effect/525537/
https://www.searchenginejournal.com/google-says-best-practices-can-have-minimal-effect/525537/