Well the way the guy described it, and I don't know details or anything, is that his sensei would tell you when you were going to test for the black belt. Brown belt students would have to be told before they could test for the black belt because his sensei required patience in addition to skill, so even if a brown belt student was skilled enough for the black belt the sensei might not let him test for it yet because he wanted the student to be patient. Again I don't know details and I could be wrong with my assumption but the way it sounded to me was that a brown belt student would have to wait indefinitely, just because the sensei wanted him to be patient.