I don't see the confusion you people have with her training. It makes total sense for her to achieve this fitness for a 6k race with just 3 running days and the rest cross training. She's only demanding about 20min of intense racing from her body. No doubt runners would struggle with anything over 10k, maybe 8k, with this type of training; the benefit of time on feet and getting the body used to pounding is the real benefit of higher mileage.
In fact, I think this is probably an ideal training philosophy for young runners (high school / early college)who don't have the discipline to take easy days easy or who are injury prone. Think of all the careers of college runners that could have been saved with less pounding on the body.