I'd be pleasantly surprised if my daughter recognized a torque wrench if she tripped over it... I can't think of a reason to dissuade a young mechanic from using one. After they've learned for a while, perhaps they'll get confident enough to skip it.

I have had a cassette lockring come unscrewed on me, fortunately just a couple of miles from a SAG stop with a mechanic (it was a supported ride). I haven't pulled the torque wrench out for that lockring yet, I just go for really tight. But I do measure the torque on my bottom brackets.