Calling your shot helps with follow through among other things.
If you are honest with your shot calls, you can check your zeros, you can check your wind calls. Basicly you can check your shooting in general.
Every shot should be called and recorded. If you'll look at a Score or Data book you'll see places to record you calls and another place to record your hits. All you have to do is compare them.
Not just shooting, but dry firing. One needs to call and plot his dry fire hammer falls.
Dry firing helps with one's fundamentals, of which, shot calling is a fundamental.
But you have to be honest with yourself. I've see a lot of new shooters, and older shooters, call "good" every time they drop the hammer. That accomplishes NOTHING.
When I coached the AK NG Rfle team, I wouldn't even tell my shooters their hit value. With the exception of some of my better shooters I wouldn't let my shooter take a spotting scope to the line. I'd give them corrections on wind or what ever, that would give me their calls, I'd plot the calls and hits.
It the calls are constant, and the shots or off, I can give them a correction. If they know where the shot hits, all to often they'd call it there.
Calling shots is important if one wants to correct his shooting errors.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071