Hi, I just saw your question - I've been doing quite a few fasts this year, sort of do 21 days up to 40 days and have had about 8 week breaks in between and haven't had any problem, feel great and have made a lot of progress. I don't think you should have any trouble doing multiple 30 day fasts in a year - There are people on here who have fasted nearly 200 days on juices! Above all - I think the main thing is to listen to your body and if you feel up to it, go for it. If you're juice fasting as well, that's a pretty mild kind of fast - you're keeping your blood Sugar pretty stable and your nutrients up with the juice. With this kind of fast it's pretty safe to go for longer periods more often if your health is all good.
Best of Luck with it - & Good for you for taking charge of your health and making the effort!