when I taught Hunters ed and bowhunter ed I discovered a couple facts. Yes, facts. I made a large model (2D) of a deer with velcro for the front half of the body. I had organs (heart, lungs, liver) wth the opposing velcro glued to it. We had the class go up and show everybody where they went, and then, where to aim.
In ALL my classes, adult, kids, everybody, NOBODY got the placement perfect, and very few got it right at all. For "where to aim", they ALL pointed "behind the shoulder", their shoulder being the point where the front leg meets the body.
We are taught this, passed on down. If you shoot low and a few inches behind this "shoulder" you will miss heart and lungs completely.
Few also understood the complexity of aiming at a deer that is not broadside and at the same height as the bowman. Changing this angle ( from an elevated platform, from angling to or fro) it changes the place where you should aim.
I feel, we miss, mostly because we fail to pick a spot. Lots of pressure at shoot time and this happens a lot.
I also feel that many of us need to spend just a bit of time reviewing anatomy of the critters we hunt. Terry has a thread going near the top of the PowWow for this very topic.
If you hit where you were looking, and got decent penetration, maybe we should discuss where you were looking.
CHuckC