If you select ''Center'' only, will it train every center on your team that has played at least 1 min (up to 48+) or just the starter ? (Same question with other positions).
your "centers" have to play in the Center spot, as backup or starter but it is best when they get close to 48 minutes there.
I don't know if the following is helpful to you, but some players get confused through the suggested position and the training for X. If you train Center and your Pg playing 48 minutes there, ghe gets full training.