I don't really have a robust working knowledge of various breathing techniques unless you count techniques related to working out or aerobic exercise or swim strokes or stuff like that.

Hof's thing I find interesting because you exhale fully before holding. I'd not really ever tried that to exhaustion before like he teaches. I've done breath holding competitions as a kid in the pool before but there you take a big lungful of air first, not fully exhaling like in this method. When I tried it, I got instant results, first cycle. Pins and needles in like the tip of my nose or my jawline...weird places for tinglies.