Dave doesn't call this hardcore. He calls this being a #hardcoredumbfuckinass. Everything in training is debatable, even if you use scientific literature to back up your position. There are studies that disagree with each other, and you can always find research that contradicts other research. No matter what, though, you have to recover. Whatever your frequency of training is, you have to be able to recover. Dave squatted every single Friday for many years and almost never wavered from this frequency. This may have worked for him, but could he have also squatted more or less frequently and been just as strong? This is why you need to remember the minimum effective dose principle: you want to do the least amount possible to gain the greatest benefit.