No one is entirely clear on how much less training a guy gets when minutes are below 48+.
Conventional wisdom holds that the drop is rapid, and that in the range of 40 minutes, training is substantially reduced.
But I think if your trainee gets 47 minutes, it's not bad to stick to one position training. Sure, you could switch it up to a 2 position training where your guy has 48+ (like JS, 1v1, or RB depending on what you're training).