Why do they call it "failure drill?"

[RM]

What is the derivation of the term "failure drill?" Is the term used in both idpa and ipsc?

[nhhillbilly]

Two rounds to the center of Mass. (IE Chest area fails to stop the threat because to drugs, Alcohol or body armor.) The third round to the brain, AIm for the nose, eye area and it will in all probably put out someone's lights right away.

[Jim Watson]

It is simulating a failure to stop in a gunfight.
I.E. you shoot an opponent twice in the torso and he does not cease hostilities and fall over because of armor, drugs, or sheer meanness. So shoot 'im in the head.
Hence, failure drill. Sometimes called Mozambique drill because it was supposedly employed there by a VIP or his bodyguard.

[RM]

In a correct failure drill, do the 2 rounds to the chest have to be shot before the one to the head?

[PBIR]

Theory I learned was two center mass semi-reflex shots pin your target, giving you time to line up the head shot.

[Damon]

A standard response is two center of mass. A failure is two center of mass with no effect, followed by one to the head.