From my experience training more than 40+ min a week will still be good addition to his current skills.
I've always seen people saying that 45,46... min are not enough but as i've seen in the past any training will count for something.
An exemple from this season:
1 player that played from 35-42 min a week on the training position (he was the 3rd player on single position), aged 26 with MVP potential, the training was passing he got in 7 weeks of training 2 pops in passing 4 weeks between them and 1 pop in handling and 1 in driving.
So let's way we don't count driving and handling, but in passing 7 weeks of uncomplete training and 26 years for 2 pops seams reasonable.
Maybe if he could get 45-48 min he would of probably got a third pop but not certain because of his age, the pops where from respectable to strong to proficient.
So maybe you 95% of training but still good enough in my book.
As for 48+ means that he has anything more than 48:01 min played and 48 min means he has no more than 47:59 min played but i think this is common knowledge.