Yes I have 12 players, 2 for each position plus a spare guard and spare bigman for injury cover and playtime issues.
15 players it's impossible really to get the full 48 mins per player from 3 games a week, but with 12 it's possible to get around 40+ usually for all the guys so they all train well. Only usefull on team training I know (not when doing guards only or something) but at the moment that's what I'm doing to get an all round team before training youngsters for profit etc.