I have seen it said here a bunch of times, and it has happened to me too, we all tend to shoot better when we pick a spot rather than shooting at a big bulk. Woodsman3 compared his shooting at 3D targets with shooting at squirrels. The 3D targets are often big animals like deer, elk, hogs and bears where people just shoot at a large bulk. Squirrels are small targets that make you choose a spot, because they are only the size of a spot. I nailed a rat though its tiny shoulders at 15 yards in my back yard a few weeks ago while I was target shooting. My shot at the rat was far better than my average shot at the 2x2 foot target! I think it was because I was concentrating on that little spot. It takes me effort on every shot to do that on the big target, and sometimes my concentration is off which causes my shot to be off too. I don't know if that is a good explanation, but I doubt Woodsman3 is just making up that story to sound like an idiot.
Allan