Judging range or distance.

So often deer/game is hit high, low, or missed entirely because of our inability to range properly. This is all part of practice, of course. I'm just being a little more specific of which part of practice I feel is most important. All the high dollar range finders in the world can't be relied on. You must practice being able to hit your target at an unknown range and incline. Almost instinctive I'd say.