When I fire a rifle, I never blink, so if I've moved off-center, I can usually tell. That's especially useful when shooting offhand at targets. When shooting game with a rifle, I don't shoot unless I feel at least a 95% chance of hitting a quick-kill zone.
Many novices blink at each shot fired, especially with higher-recoiling guns. I suspect they're jerking the trigger, because they seem to know when the gun is going to fire and often blink a millisecond before the gun fires.
If you watch American Guns and Page shoots, watch her eyes. I said her EYES! LOL