Is it considered and exception for mental health, or just physicians/surgeons/ect? I have a hard time seeing it as an exception for Troi, as opposed to for Crusher. I guess it's an issue that they live on the ship, all the time, for years. It's not clear how much of their time they spend at Earth or on starbases, because most episodes aren't about those types of situations.
Picard and Riker seem like the same sort of situation, since everybody reports to them.
> However this raise the question of why there is only one therapist in the entire ship?
Yeah, I've seen other people point this out as well. She also spends alot of her working hours on the bridge, does personnel reviews, and is advises on contact with alien cultures, which presumably requires research and writing reports in addition to the kind of stuff we actually watch her do with that aspect of her work.
I assume that everyone on the crew is at least supposed to have an annual mental health checkup. If she's actually the one who does that, and not somebody else when they're stopped on Earth or on a starbase or something, then that's probably 17-20 hours of her week right there.