well offcourse in combat situations, you use as much fully loaded mags as you can...But in training, like on shooting range, its almoust dangerous if everyone has the fully loaded rifles/SMGs on hand. The situation satys at hand far better when the drill instructors order the troops to load whit let say like five rounds to each of the three mags. Then the troops shoots them by some training program. and after the shooting is done, there supposedly isent any fear of loaded weapons when the men have to travel to the targets to see how they have hit.