There are some lazy ass SCHs in this game. I keep running into one in DF runs that literally just stands there and does nothing. Only started doing shit when I called them out.
Well, you have some SCH who just follow you and let their fairy do all the work (and it is enough in some battles), which is indeed quite infuriating. A good SCH should DPS in dungeon, unless the tank needs healing of course.
Sadly, it is not only SCH: a lot of WHM too do nothing but healing, when they perfectly could help with DPS (Regen is often powerful enough to keep the tank alive, allowing you to go into Cleric stance and Holy-spam the mobs, with the added sweet effect of stunning them, or the classical Aero II, Aero and Stone II spam).
I also met a WHM who never used Regen on the tanks during T6, something which baffled me. I had to ask him to use it. Oddly enough, things went smoother afterwards (2 Regen do wonders to a tank's health).