Almost every time I've been able to get 48 by making that player the starter/backup/reserve, leaving all other reserve spots blank, and making any potential reserve players inactive (in other words, only have 9 players dressed out in the "Selected Roster"). There was one game where this still didn't work, and in the last minute a different position's backup subbed in for no apparent reason - and I guess this is the "bug." Otherwise this has been about 99% reliable. (But it's still not "strictly" following the depth chart.)
I've experienced this same 99% reliability when I aim to play my trainees 48+ minutes. Maybe sometimes they sub out for 30 seconds on a FT and only get 48 and not 48+. Even if it was only 90% of the time that it worked, I'd say that is still fairly 'strict', and not remotely 'vaguely' or 'loosely' following the depth chart.
In the end, the training is just about the same. I don't really understand what everyone is so fired up about.