Originally posted by Isaac_Clark:

If you only click on the beat your character will get tired way before your hand does. Don't spam. Click to attack once, then after the attack animation has completed click again.

Try playing some "Git Gud" titles to improve your "Git Gud". Like Sekiro or any of the FromSoftware games.

Obviously there is no way for you to know at what point somebodies else's hand gets tired.