If the target is a 16" black circle on white background and you got time to do that NRA breathing thingy.
If the target is full size human target in fair to good light.
If the target is 10" orange circle in bad light.
If you're running irons, red dot, good scope, great scope.
If you're running something that you refused to pay a bunch of money for.

It's a competition. It sorta tells you where you're at right now. Out of breath, can't see target, didn't know where to aim, couldn't get comfortable or get on target, gun jambed, mag jambed, mag was too long or too short - whatever! Now you know what to work on/fix.

Competitions are not defensive drills. However, I really don't see how they would hurt when you do choose to do defensive drills, or have to.