I guess in a few occasions team training can be effective... but until we reach the high salary caps probably not..... im interested to learn the decrease in effectiveness from training 2 positions to 3 positions....
i think if you buy your players young enough then interjecting a few team training weeks is fine if this can improve your roster significantly enough to not have to keep upgrading your non-trainees... 18-23 yo is a long period of time... you should be able to make some massive improvements to your players skills... however if you are training 20/21 yo then the few weeks here and there with team training may not be as appropriate..
just my view!