I don’t think it’s ever too late. Obviously it can be difficult to untrain bad habits, but it’s really just about sitting down and consistently doing the work. Forcing yourself to slow down can feel super tedious a lot of the time, sometimes you need to go like agonizingly slow for longer than you really want to in order to crack the part you’re working on, but it 100% pays off if you do it. And a lot of time you’ll eventually have to go back and do it over again because certain sections got sloppy over time. I still have to do it even after 30 years of playing. I don’t think it ever really ends.