If I find I am receiving recommendations in which I am uninterested and are clearly based on a handful of videos I watched previously, I can clear those from the history and the algorithm doesn't use them for future recommendations. The simplest example would be watching videos for a one-time use case such as repairing a specific home issue. I definitely don't need more recommendations to fix that/related issues, but YouTube is likely to spend a little time sending them my way. I can fix that quickly by removing the original videos from my history.