In my experience it doesn't work that way. Most of my bows have not been cut to center, and I sight straight down the arrow to the very center of the target, and that's where the arrow hits...if it is spined right. The shallower the shelf, or the farther away from center, the weaker the spine needs to be to compensate. But if your arrows are tuned right, I don't think you need to adjust how you sight/shoot regardless of how shallow or deep your shelf is cut. I even shoot and hunt with selfbows with no shelf at all; I shoot off my knuckle and still sight the tip right in the center of the target.