I think, theoretically, insulin should be lower and growth hormone higher on a 3 day fast.
Maybe the best option is to mix the two? One week of 3x/week; one week off; one week with 3 days straight.
I found that I could do too many 36 hour fasts, and it got so that I was freezing when I tried to fast any time at all. I had to take time to recover. So, I’m not a big believer (anymore) of doing a lot of fasting, without “enough” feasting. The trick is to determine how much is enough feasting.
Right now, I’m just trying to get back to one 36 hour fast per week. That might be all I do, until I do a long-term fast, probably 4.5 days. That’s one I can fit into a week, so eat Sunday evening, then again Friday morning sometime.