I honestly don’t know.
I know I can do 3 minute loops. I also can do 15 minute loops. The 30 second loops were terrible for me. I don’t remember if I tried 5 or 7 minute loops.
But as for me, I’m not going to do 30 second loops again any time soon.
What I can say is that I’m glad 30 second loops are working out for a number of people.