Can you say what it is you think that fucked up your dogs? Or do you simply think there is not enough strength training integrated in lemmens keep?
I don't know what kind of dogs lemmens was feeding, i can imagine someone with a line who are strong naturally or depending on fighting style, would consider strength training less important. Doesn't mean its a good keep for all dogs.
About interval training on the mill, I think you have to have good eye for when its enough of "all out" for the particular dog on the mill, in the particular stage of keep. Same counts for recovery. When you leave the room or show the dog a bait or animal they might give more then they supposed too. When these dogs scratch with 2 broken legs, why would you count on them to indicate muscle pain or overloaded ligament.