Edit: I didn't add the second paragraph in the Game Manual in my previous post, but it should be amended too, as it seems quite evident that it gives the false impression that: 1) you need 48 minutes for training; 2) SFDC is the way to go to "optimize" your minutes. How is that not misleading? If I was reading that for the first time, I'd assume that SFDC will allow you to get 48 minutes and will also prevent the coach from starting subs or playing them more minutes than the starters (as it happens with Coach Pick from Depth Chart).
Except that "optimizing" does not equate to a guarantee of 48 minutes, just that the SFDC option will give you the best result of the available options (with all other factors being equal, at least; you'll likely be more likely to get a trainee 48 minutes on a CPFDC with only five players dressed than you would with a SFDC in a blowout win with 12 players dressed).
That's also why they say that it gives managers "better control of their training minutes each week" than "gives them control". You can be reasonably assured of a general minute split depending on the game conditions, more so than with other lineup types. The fact that it's still well beyond your control overall, of course, is something that could definitely be improved - though I more frequently lament not being able to get players with respectable+ stamina under 44 minutes in a slow offense than losing a few minutes here or there.