Yes, calling your shots is a fundamental skill for competitive shooting. A decent practice for learning it is this; take a 1/3 size replica of your target to the line with you. Fire, and mark (without looking) where you think the shot went. Use an "x". then look at the target, marking the actual hit with an "o" and connect them with a line so you know which string they are from. When you can do that every time, shoot two, then 3, then 4 and so on. Then start using a timer. You're going for .15 to .2 splits while being able to call the seperate shots accurately.

As far as defensive shooting goes--I'mthinking you're asking a lot. The way your brain works under an adrenalin dump is different than it works at the range. You may not know how many shots you fired, let alone where they all went! And? Most defensive shots are point shot--not aimed--out of necessity. You duck and run, point the gun in the general direction, and hope for the best. In the rare scenario where you get to aim, yeah, I think calling your shots is hunky dory.