If you're focused on C/PF typically worthwhile to start with defense training and take that to where you want it. That creates an elastic effect that makes Inside Shot, Rebounding, and Shot Blocking train faster. Obviously you'll have to take into account the levels of the players you're training and where they are starting. If doing two position training each week for guys 18-21 or so, you should be gaining a level every 3 weeks or so, adjusting for the height advantage and age.
You can also go with Inside Scoring, since the other big focused training types will also train scoring. Allows you to get to the number you're comfortable with and allow the extra training to push them higher while building other skills.
In terms of minutes, in seasons where I think I'll be generally uncompetitive, I rotate my starters to maximize their minutes. Game one player 1/2 start with 3/4 on back up, then next game rotate. Game 3 is new guys and they play 48 minutes. This will usually get you to 48 minutes. Only concession I make is to play my better players the game I think I can win and then see where the other lands. You can also just play your guys 48 minutes each game and just rotate. That guarantees full training each week but will generally sacrifice a game a week when your training backups play.