Dr Clark recommends two weeks between flushes. I was able to verify that this is the correct timing but measuring changes in athletic performance. Peak performance always occurred around 10 days on average, which means that I was not only fully recovered in 10 days, but I was performing at a higher level than I was before the flush. For me it took two flushes to clear the "external" skin infections. I'm sure that it takes more than that to clear the internal issues.
Play it by ear. If you decide to use The Clark Flush and don't have trouble with the first flush and start to see positive changes, then I would continue to perform them every two weeks until you're at least satisfied with the results.