Muscles need time to repair. Generally ~48 hours, but depends on how much damage was done, type of training, size of muscle, training status, etc. Analogy from Dorian Yates: if you scratch the palm of your hand with sandpaper pretty good and give it time to heal, callous will form. But if you scratch it again before it heals, you get a bloody hand. Recovering properly from exercise is about as important as the exercise itself. If itâs getting harder, it may be a sign youâre actually destroying more muscle than youâre building.
Discussion
There's a reason why the top athletes spend a lot of time laying or sitting around lol..đ
Dorian Yates trained 4 times a week and won Mr Olympia 6 times in a row. You donât need to train the same muscle every single day. 
This explains why two days off from playing beat saber seems to massively improve my performance.