Team training is a bad idea. You get very little rewards. You should focus on training 3 18-19 year old players using 1-position training.
The more positions you train at one time the less effective that training is.
A few skills like Rebounding, One on One and Jump Shooting can only be trained with 2 positions at a time. Anything else should be 1 position only.
If you try to train an entire team at the same time they will all be terrible forever.