My opinion on this is...I keep everything as clean as possible and have my torque wrench calibrated every couple of years. I watch very closely on what I do. and when I assemble an engine I am by myself, no one around and not even the radio on, so there are no distractions. So far I've had pretty good luck. I'm like alot of you...can't afford to have someone else do it. And have the pleasure of saying "I" built the motor. JMO
TS1955