Presence of mind in a firefight is not a common trait. Usually it is melee attitude for most folks, meaning that you swing until whatever you are swinging at is either on the ground or running away faster than you, or else you get too tired to keep swinging. I don't see as it differs much in a gunfight. Most will keep shooting as long as they perceive a threat, until the threat is diminished or they run out of ammo.

I was truly impressed during a gunfight in Iraq wherein our security group got ambushed and was returning heavy fire. The group leader pulled his drum magazine and replaced it with a new one with less than five bullets left in the old mag and a round still in the chamber. After 95 rounds at full auto bursts, I doubt I would have the presence of mind to not end on an empty chamber with an empty mag. I think the 5 security guards expended something like 2,000 rounds in a little over 2 minutes, pretty much neutralizing the threat and affording an effective escape with no casualties.