While I have similar thoughts to some expressed above, that theoretically the 3 under grip should not function as well on a short bow because the difference in force applied to the top and bottom limbs would be amplified on a short bow, in practice I have not found this to be the case. The shortest bow I shoot is 58”, so it is possible that even shorter bows might result in more noticeable differences. Obviously, a 58” bow is going to have more finger pinch than a 64” bow; the laws of physics can't be ignored. However, my 58” Robertson Wolfer shoots and bareshafts fine 3 under. It was ordered to be tillered for 3 under, so that might make some difference, but frankly, I haven't noticed much difference over the years in bows that were tillered for 3 under and those that were not.