Battle field load stacking.

[Tim Maxey]

This phenomenon was, if memory serves, the reason for the bolt hold-open feature on Mausers. Panicked soldiers would continue to work their actions long after their rifles were empty.

 

[Pete G]

Yeah, that's were the drilling/training comes in, your hands still know what to do while your mind is scared spit-less and barely working in any cognitive way.

When under high stress you will perform per your training.