Overboard? Not even close. The duration and frequency depend of your goal, but all things equal, the longer the fast, the better -- up to a point, of course. Actually, 16//8 should be the norm and typical for most people. But the benefits derived from fasting continue well past that.

On the other hand, my 24 hour fast is intended to reap more of those benefits but is not as regimented as my daily fast. My point there was that it can be done, and without any loss or deleterious affects on your physicality, your mood or to your personality once you've adapted. In my research and experience, the benefits of IF continue to expand up to 48 hours. After that point, the benefits may continue for some, but the overall curve starts to diminish significantly.

For instance, if maximizing muscle tone, strength, and size are your goal if could begin to have a negative effect after that point. That is, someone who works at a desk may get away with it. However, someone who has a physical job may not.

In other words, going from 16 to 30 would net you a big improvement from fasting. But going from 30 to 48 are not nearly as profound as the first jump for people under a strength/tone regiment like myself. A relatively small amount of benefits for my needs, and not really worth the effort.

Just keep in mind that the length and frequency of your fast depends largely on your goal, and to a degree your physical condition and your diet. If you are a steak eater for example, it could take up to 72 hours after you've finished your meal for it to run its full digestive course and be completely out of your system. Just one example, of why you might want to fast for longer.