yes - training the whole team should be slower than just concentrating on 1-2 or 3 positions - you are effectively spreading out the improvement... so you can improve 3 players very quickly when training 1 position or lots of players thru the whole team if you train a team regime.
it hasnt been confirmed how much more slowly the team training is because most people prefer to train 1-2 positions just with very young trainees...
there is benefit to team training but i think financailly you will not improve as quickly as if you choose a more intensive training programme...
take a look at
(381.1)hope this helps