Practice makes perfect is a thing, but that's not exactly rehearsal.
With practice you expect to improve, broaden, or maintain instrumental or musical ability for the long term. There should be no deadlines or need for actual listenability.
OTOH rehearsal is the run-up to a smooth listenable performance with a decidedly short-term objective by comparison. Unless you are rehearsing to absolute perfection, you do not halt for anything, the show must go on and that in itself requires you to practice covering up and compensating for your mistakes or shortcomings as you go along.
With practice you are actually trying to become a better player overall, but rehearsal is more about making the next performance as good as it can be and that's it.
If you're not actually as good as you would like in either regard, having a bit of commitment to simulating what you need most can give some direction itself to add to the mix.