At the French Pastry School, chef Dendauw taught us how to make brioche using the "slapping" technique and also in the kitchen aid mixer. The results were identical. I got so slap-happy that I lost track of time in class, but I would guess it took around 30-40 minutes. There were a couple of differences from the technique in this video though. We used a motion where you grab some of the dough, stretch it towards you, then cut it with a scraper. This was to cut the gluten chains and not develop too much gluten (I think). About halfway through the mixing, when the dough came together some, we added the butter (instead of at the beginning as in the video) and after that, used just the slapping motion until the dough was fully mixed.