I've only had to check the valves on my SL 5-6 times and had to adjust them 2-3 times so I'm certainly not an expert. It's not like I work at a Ducati dealers and work on them everyday...
The valves are the trickiest part of servicing a 2-valve but only from an access point of view as Alan says, however engines don't get much less complex than the DesmoDue. They're only one step up from C90s... Compared to checking or worse adjusting the valves on a Japanese IL4 with 16 under bucket shims (or God forbid a VFR V4 with VTEC) it's a piece of wee wee...
Getting to the shims for the vertical cylinder requires you to take off the rear shock and remove the battery and a few other bits. The bike's having a service anyway so the fairing and belts are liable to be off. Worse case is the closer shims need doing on the vertical cylinder but 4 hours (say 3 1/2 hours if you get the trainee to undo the 2 bolts holding on the shock and the couple to the battery...)?
It's a fallacy that
all Ducatis are difficult and complex to work on and require the skilled and trained hands of surgeons to fix.
Darren