With adults longer periods of time are in the 1 - 6 month range. It is shorter with children.
Chlorine dioxide and chlorite are biocides. That means that they kill living things. One issue with drinking solutions that contain these chemicals is that it can upset the balance of flora in your gut. If your flora is already unbalanced you can see benefit at first, but then the benefit falls off with extended use.
The idea of pulsing is to start by killing things off then following that with providing the body with the building blocks it needs to re-establish a balanced flora and a healthy body.
An excellent book on the rebuilding process is Minding My Mitochondria by Terry Wahls, M.D.