If you’re continuously generating content and you want to stay abreast algorithmic changes, you’re never going to be finished with SEO. Search engine algorithms are constantly being refined to create a more user-friendly experience. This means that SEO tactics that worked ten years ago or even one year ago might not have the same impact that they once did.
Additionally, your business does not exist in a vacuum. If you are performing SEO tactics, your competition is probably doing it too. All else being equal, if you stop putting in SEO time while your competitors continue, the competition will start to pull ahead. As more and more companies partake in these optimization tactics, it becomes even more integral to step up your optimization game in order to properly compete.