How big a torsion bar nick is ok?

Owned Mopar my whole life, never broke one. And before I knew better would use a pipe wrench to grab the bar and knock them out with a hammer when rebuilding front ends. I would stick back in and run them. Never had a failure. Maybe I was lucky? Could it fail? Maybe. Those bars are tougher than some would have you believe. In normal use they are subjected to all kinds of road hazards and debris attacking them.