It is important to be clear on one thing regarding drills. If you use a drill or drills know why you are using the drill. In my experience drills are most effective in closed skill activities where they can be used to correct a part of the movement or reinforce a concept. But always go back to the whole movement, remember Whole – Part – Whole.
In any situation drills are most effective when the athlete has a clear image and feeling for the end result – the whole action. I know from personal experience that the longer I have coached the less drills I have used. My menu of drills has grown but the actual use has decreased. For me drill are highly prescriptive to the individual athlete.