I also agree that this is a good question, there are many variables to consider on this topic IMO. (One thing that I happen to know is that Loneranger often, and maybe always, hunts from the ground. Being on the ground with the quarry v. being above them in a tree stand could influence the impact and effectiveness of a "MAAAHH" too.)
I have shot at three deer walking in my life and in all cases I ended up with a hit that was further back than what I wanted. Two of these were nice bucks responding to a decoy and I could not stop them with the normal "MAAAHH", they were too dialed in to the deke to listen IMO. Both shots were about 12-14 yards, so fairly close range...but still the slowly moving target at close range resulted in a hit that was "back".
I do think though that if you practiced leading them say 6" you would be OK at close(10-15 yards) range, but for me, that apparently is too much to remember at the moment.
I almost always will stop a deer prior to the shot and I have had even had to yell "hey" at the top of my lungs a time or two. But...if the deer looks tense...aim low, because they will drop. And the further they are away, the more that drop will impact where the shot hits...or does not hit. BTW, there is nothing like having the shot on video tape to see later how much that a given deer can drop at the shot. What could have been a solid double lunger, can end up as a whiff over the back in the right situation.