A lot of people believe that SEO is one-time work, however, it is not true. In order to remain in the game and hold your position firmly (your rank on search engine result page), you need to frequently update on Page SEO. Updating on-page SEO means you add relevant keywords (primary as well as secondary), use trending keywords, update your content with new information, remove outdated content, etc. You will have to update on-page SEO every time Google runs an update.