Ofcourse of lot could go wrong, but why only pick 4 while you could have 6. I am currently doing 1 position training for 2 PG's and a PF with low potential who I want to make an allround backup player.
I break this up into 2 pieces however, where I will always make sure my U21 player gets his 48 minutes, as well as my 18 year old American. Should they foul out, or get an injury which doesn't last until after the match, they will play starter/backup/reserve depending on how many minutes they still need.
For example, my U21 fouls out:
- Played ~36 minutes, still needs 12 minutes, so I will play him backup+reserve in my scrimage to make sure he gets the 12 minutes, but doesn't get too many either.
- Played ~ 47 minutes, still needs 1 minute, so I will play him just as a reserve in my scrimage
- Played ~ 10 minutes, still needs 38 minutes, he will play starter/backup/reserve as this is the only save way of knowing he gets 48 minutes of training.
Should this situation come up, my PF will be the one who doesn't get full training. Pick 4 main guys and 2 extra trainees, or as in my case pick 2 main guys and 1 extra trainee.