Not strictly true actually. 48 minutes does not give 100% training, as the listed 48 minutes is a rounded up value that really is 47 min, 31 or more seconds.
Still, the loss in training is likely to be small. I usually don't worry about training minutes until they get to 42 or so (depending on the importance of the trainee). That's the level where I might consider switching to a 2 position week if that would get more guys their 48+ min.