Like many of you, I'm more concerned with what is a poorer than average group than a good group. Kind of a worst case scenario group. Murphy will guarentee that is the kind of shooting you will doing when a 360 bull elk is quartering away at 50 yards.
Having said that, a high percentage shot for me is a tennis ball at 20 yards or a grapefruit at 40 yards. Sometimes I can do the tennis ball or better at 40 yards, but not reliably.
My hunting partner is so good that if he didn't shoot at a different dot each shot, he would go through a dozen ST Axis arrows a week. Continually breaking nocks and tearing off fletching. I like where I'm at. I'm good enough to never miss the block target and not so good that I ruin arrows. A dozen shafts last me a long time