"Ball pressure buys you time"
If you always have good pressure on the ball then that will allow your teammates extra time to get through screens and recover to their man. You never want a passer to be able to sit back and put a pass exactly where and when he wants it. Even if you get caught in a screen or get back cut, if your teammate is applying good ball pressure, that may be the extra second you need to recover to your man and not allow an open shot.