I never had to worry about a deer shooting back, so making sure he dies on the spot isn't the same concern for me. Also, I always plan on eating any deer I kill, so the less shot-up he is the better in my opinion, and the last thing I want to do is just sling lead at the back end of a running deer.
I try to only take a shot I like, if the angle isn't right, or if it's obstructed the safety never comes off, he gets another day.

After I shoot, I'm a lot more interested in seeing what he does & where he goes, if he's flopping around I might jack in another round, but really I usually don't even think about it. I guess if I have a clear line of sight like hunting in a big open hollow a second shot might be doable, but hunting around pines with thick little hardwood bottoms like I do, you'd pretty much have to be satisfied with your first attempt, the second one would just be at the brush waving where he went through.