I think moving on the shot may not cause you to miss the present shot but it will cause you to miss future ones. Forcing yourself to stay still and experience the totality of the shot helps ingrain the shot into your subconscious. You can sort of experience what I'm talking about if you miss a ball on purpose while forcing yourself to stay still for an extended period of time. It's a bit uncomfortable. Once your body and mind know that there's no way out, you start approaching shots a lot more solidly. This really helps with aiming of all things. Players that struggle with aiming really don't experience their misses as thoroughly as they should. Staying still is super important as far I'm concerned.