also you have to be REALLY strict about the stuff you watch - if something comes up that you don't like the look of you can instantly swipe away. that trains the algo more accurately than saying you don't like something using built in tools but you can do that too if you really object to something.
for me it usually takes less than a week to train a new account to specific content, less than a day if it isn't niche("gaming" is easier to train than "gym exercises focused on strength over hypertrophy")