When you are perfectly healthy, you don't need to cleanse anything.
Most people who have health problems don't even know what the perfect health is, cause they are so much used to not being 100% healthy.
Or when you just feel like you are healthy enough. It is your choice.
I read on this board about ten years ago that you are only good when you have two clear flushes in a row, like two flushes where you don't get any stones. Is that still valid?