I don't think that any of us "one shot, one kill" guys would dispute a "mercy shot!" But where I hunt, you rarely would get a second shot anyway!
I'd bet dollars to doughnuts that when you hear someone emptying a gun at a deer, 9 out of 10 times, every shot missed!
I'm not claiming to be the best shot in the world, but if you didn't hit a calm, still, broadside deer, with a well aimed shot, what are the other 3 or 4 shots going to be? Hail Mary's!!!!