Wayne, What I was trying to illustrate:

torque give you an approximation of the tension relating to a stree/strain graph.

Measuring elongation gives you the exact point on the stress /strain graph. So that you know the fastener is below the yiled point.

heck i use the torque wrench I inherited from my dad when I build my engines.. I have never had a fastener failure.

Its usually operator error. (missed shifts) that i have to deal with