Okay, so I then I did sort of get it, except that I just didn't know that minutes towards training are capped at 48 minutes.
So in training considerations: 9 minutes = 9 minutes, 24 minutes = 24 minutes, 48 minutes = 48 minutes, and 91 minutes = 48 minutes.
Don't ask what sort of Chunks they are, you probably don't want to know. Blowing Chunks since Season 4!