If you really really wanted to you could specially train someone to monitor calls for specific issues and that one person could potentially listen to every call three or four reps make. You'd have them listen to all of the calls at twice the speed and use playback software that cuts out any silence (if you're looking for dead air, that's easy enough to do with most call-analysis software without listening yourself).

That's basically just me spitballing the closest thing I could imagine to that, and I doubt they're doing either.

I wouldn't be surprised if they do run a whole lot more quality assurance checks on new reps than tenured ones, but that'd be pretty normal.