I don't rely on faith alone, either, but I do tend to believe what I was told repeatedly by GM field engineers and training center instructors for the 20+ years I attended their courses and interacted with them in several top-rated shops.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!