BobCo, the explanation is simple. LETOFF. You aren't under the strain of holding peak weight at full draw and that allows you the time to settle in and get everything aligned just right before dumping the string.

No, I don't shoot off the shelf. I use a flipper rest in the standard position. It is quicker to learn to shoot a canted bow off the shelf, since it's closer to your hand and natural pointing ability, but it's not at all difficult to shoot off an elevated rest. Concentrate on getting the nock of the arrow directly under your eye and align the tip with the target. Eventually, your hand/eye coordination will make the adjustment and you don't have to think about it.