I think you could probably do 10 every 30 days if you really wanted to. 20? I’d probably say safely every other month? I did a 50 day straight fast early this year netting 60lb weight loss, and then ate for a month before doing another 10 days. Following that I mixed in shorter fasts of 6 and 1-3 days until now, and I’m currently pushing for a potentially 25 day post Thanksgiving fast to hopefully drop me to a new low weight and a lot closer to my goal weight (180ish lbs, 6’2”m - fasted from 158ish -> 197 on my 50 day fast, and have bounced between 195-215ish since). Aiming to hit or pass my target weight by the one year anniversary of this journey.