The complication we run into most in this area is a door that's been forced back onto the track by hand before we get there - understandable, since a stuck car in the garage is a real problem, but forcing it can bend the track further or crack a roller stem that was otherwise fine. If that's already happened, the visit takes longer because we're now diagnosing damage from two events instead of one.
The other one is springs. A door that jumped track under tension - meaning it happened while opening or closing rather than sitting still - has usually put stress on the spring system at the same time. We won't put a door back into daily use on a track repair alone if the spring's compromised; that's the honest limitation here. Fixing the track and ignoring a stressed spring just moves the failure a few weeks down the road, and we'd rather tell you that upfront than have you call back for the same problem twice.