When the worst happens is not the time to be testing the systems. We didn't use it on 9-11-01 because we didn't have it. If you don't test it you don't find the bugs.
My son was sitting in a high school class when they ran an armed intruder drill, his substitute teacher thinking it was a fire drill insisted that all the kids leave the class room. My point is if you don't test you don't find our where the bugs are.
Eric
"Complexity is easy; Simplicity is difficult."
Georgy Shragin
Designer of ppsh41 sub machine gun