I have noticed that when shooting from high up in a tree, I generally hit a little higher on the target than when on the ground. It is much more pronounced at close range (10 yards or less) than at longer ranges. I forgot about it last year when taking a close shot on an 8 pointer. I was aiming for the heart on a quartering-to shot (I know, not recommended) and the arrow hit about 6 inches high in the base of the throat. Thankfully the arrow severed some major arteries and the deer fell within sight.