How effective are modern diagnostics at finding intermittent electronic faults?
 

It used to be that some kinds of problems (mostly consistently demonstrable ones) were easily diagnosed and predictably (if not necessarily cheaply) fixed, while others — particularly intermittent electrical faults — were a predictable torture sentence of repeated dealer trips with "no trouble found" dismissals.

How good are modern diagnostics at tracking down intermittent COMAND problems? I have occasional failures like "completely blank screen" or "failure to activate backup camera (even though mechanical cover opens)" that are cleared by a restart of the car, and I'd like some idea of where on the "abandon all hope ye who enter here" to "no problem, they'll read out a trouble code and replace the faulty part" scale I'm likely to be.