This guy says the same (around 20 mins), once every 2 weeks is enough for muscle maintenance specially for skinny guys.
As an afterthought, on the matter of controlled hypoxia being a good thing, per the first video in this thread, I'm reminded of the Wim Hof breathwork method. During the breath hold periods, my oximeter reading sometimes goes as low as 35. I suspect this is an inaccurate number because the pulse oximeter is reportedly only accurate to a low reading of 70. But I think I can safely assume my level went somewhere well below that minimum threshold.