During a recent shooting slump, a friend of mine who was watching me play pointed out that my bridge hand seemed to be moving slightly on my final stroke. I started trying to notice what that hand was doing during my next practice session and realized that I was making tiny, unconscious aim adjustments with my bridge hand during warm up strokes. Now maybe it's OK to make those little shifts of your hand during warm up strokes, but for sure you don't want that hand to be anything but solid and still on your final stroke. When I started focusing on locking down my bridge hand on my last couple of strokes, my ball-making accuracy improved immediately. I guess one way to think of it is that you want to eliminate as many variables as possible and keep as much of your body as still as possible as you deliver that final stroke.