20's I wouldn't say are hiit. That's a different energy system, or at least contribution of energy systems from what hiit is.

I would say hiit's duration of each "rep" would be about 3min maximum. And that's pushing it.

I'd say hiit is more in the 1min range and less per rep.

Could be 1:1 work. Could be 30s/30s stuff. Could be 40/20's. Whatever.

While the intensity of 2x20s can suck given the duration, I don't think that's the energy system they had in mind with all the studies talking about it.

Just IMO.