I think you misunderstood what I was trying to say. You need three players in every game to have a valid line-up (and to accumulate minutes for training). Also, I was assuming a single position training program, which usually means you need to get each trainee exactly 48 minutes at his training position.
So, let's assume you have 3 trainees: trainee A, B and C. You also will need 2 scrubs: D and E. Here is the rotation I would use:
Game 1
A gets 48 minutes at the training position
D and E play at other position(s)
Game 2
B gets 48 minutes at the training position
D and E play at other position(s)
Game 3
C gets 48 minutes at the training position
D and E play at other position(s)
Not optimal for game shape but certainly better than having no players at all. At least you still get training.
As for whether this is an good strategy or should be made illegal, I have no opinion. I will leave that for others to debate.
Run of the Mill Canadian Manager