When I first got out of the military in 1970 I was all caught up in the 3" high at 100 yds theory, after a few years I figured out that I was always either shooting over big game or hitting them in the spine. I think a 3" high zero is fine if you are shooting antelope or some other animal on flat ground, the problem here in the west is, you're almost always shooting at a steep uphill or downhill angle. Very seldom does anyone miss low, they always shoot over, at least thats been my experience in 50 years of shooting game.
I call it the old 30/30 syndrome, that is, hold center & then elevate a few inches for drop (not needed) & slip one over the top, happens everytime!

Dick