They don't stay long in mine, either. However, they do learn from the teacher. If anything, they seem to learn more than in VV4. There, 14-year-olds would 'graduate' as adepts, but only just above the trainee/adept cusp. In VV5 most seem to be easily halfway though adepthood (if that's a word).
It might help that my main teacher is the former chief, who is of course a JOAT, (and is regularly rejuvenated).