Let's see. I've done:
10+ Liver flushes
10+ Parasite Cleanses
10+ extended fasts
+ An unknown number of other types of cleanses and detox diets
I don't really have a set time as far as how often I've done them. The liver flushes and parasite cleanses were more at the beginning of my journey toward health, whereas the fasts began happening later. Now I try and do at least 3 juice fasts per year. I believe I've only done one so far this year, and am getting ready to begin another one here pretty soon. I have another one planned for November. Spring and fall seem to be when I do the most of them.
But pretty much I just rely on my instincts and do them whenever my body begins telling me that I need to. Whenever I feel the need to "reboot," so to speak.