I’ve been reading the “Science and Application of High-Intensity Interval Training” by Paul Laursen. I also listened to him on the That Triathlon Show podcast. He was talking about 10/10s as more aerobic short intervals, being so short they don’t hit anaerobic systems.
I tried two sets of 5 minutes yesterday. They were a good workout! They did have the effect of a steadily increasing HR to the point that I was getting near VO2max towards the end. My average power for 5 minutes was around FTP.
I’ve never really done short/short intervals. I’d guess that these would be similar to 15/15s. 30/30s or 20/40s would probably hit those anaerobic systems a little.