The problem with these longer fasts is refeeding. If you do rolling 120s, then you need to take time to refeed gradually which will usually take a day or two. It’s the reason why I never went that far, and only do rolling 68s and twice I did 90 ish. Even on my rolling 68s, I’m careful to not eat carb heavy foods on the first day I break the fast.
The general consensus is that you don’t need to do much of a refeed for sub 72h fasts, but for longer ones it seems you do need to take it seriously. The problem is wirh a rolling 5 day fast, it ends up being nearly a full time fast when you include the refeeds. I would not do it, stick to something shorter like mine if you like.
Though even the rolling 68, I only reccomend it if you’re severely morbidly obese like I am. If you’re normal weight range, then just do shorter fasts and much heavier exercise routines.
I hear a 7 day fast is good for once an year or so.