My instructor received his black belt from this gentleman and we do some of these drills in various forms. The cardio workout from these alone is tough. I have been finding myself also using some of these techniques while grappling.
"Unarmed hand-to-hand fighting does not change through the ages; only the name changes, and it has only one rule: do it first, do it fast, do it dirtiest."
~Robert A. Heinlein