Well what ever you are doing, it sounds pretty darn consistent for you, and that's what it's all about.
The point i was making was, that for the majority of guys out there, that flat spot in the grip allows them a spot for their thumb pad to settle into the same every time. It forces you to rotate your bow hand perfectly, and get a good solid foundation where no torque is applied to the grip.
I know a lot of archers that prefer a larger grip to help them get a consistent placement, but i'm a serious advocate of the flat spot in a grip. Also...If that flat spot is angled slighty away from the shelf, with a slightly lower thumb ledge, it allows an archer to use a vertical bow alignment with a natural wrist rotation...... For guys that prefer to shoot with a slight cant, the side to side angle of the flat spot, and the elevation of the thumb ledge can be altered to accommodate them......
I believe the grip shape is one of the most important parts of consistency in archery. Its the foundation of the whole thing.
Oh sure.... you'll run into those gifted archers than can pick up just about any kind of bow and shoot it well. But they let the bow settle into their relaxed hand the same every time and quickly figure out where the balance in the grip is located. For the majority of archers it take a bit more conscious effort.