That really seems like a wash, your later training in whatever is slowed down by just as much, plus you get your skills out of whack, which gives you a penalty to training. Basically, there are two paths, going with balanced training (my strategy) will result in a slightly better player, but will waste some resources getting there. Doing all of the single position training first will allow you to focus resources more effectively, with a loss of a little bit of training efficiency, due to out of balance skills. There is of course also a compromise position, where you do mostly one position, but during the allstar week and other weeks with only two games (offseason) you do two position training.