If you have references handy I'd love to read more. Specifically, it sounds you're saying that there is evidence in recreationally trained athletes that less frequent HIIT improves [meaningful outcomes] equal to much longer and more frequent training durations of moderate intensity cardio.

I'm much more familiar with the evidence on strength training, where it seems that volume and intensity both have important roles. But at this point in my life, I no longer have the time to train as often as I'd like!