Fix your player like thisFor example you will train C positionPG: 1-2-3SG: 4-5-6SF: 7-8-9PF:10-11-12C: BLANK- 13-13NUMBER 13 will train 48 minutes unless he fouled out or injured
Honestly, I doubt your method is doing anything different than a lineup where the trainee is also listed as the starter. It's possible your method works better, but I'd want to see more examples of games where it worked (and similar games where actually listing the starter didn't work).