Here is what I found in the manual. I'm not 100 percent sure what this means, but I took it to mean that you're not guaranteed any certain amount of training if you fall short of the 48M.........
...........playing a player 24 minutes at a training position does not mean that that player will receive 50% training at the update. Training is not linear, it is exponential.
I take the word exponential to mean there is no assigned value to the number, meaning there is no assigned training value to 47 minutes or to 20 minutes, meaning you could get the same training for 20 minutes that you receive for 47 minutes. At the same time, I take it to mean that you could actually get more training for 20 minutes than you would for 47 minutes because it is random.
Again, I could be wrong on all of this. I'm only stating my opinions for purpose of conversation.