I think if you get some feedback from hanging veterans, they'll probably say you should hang every day, no rest days. The reasoning behind this is to prevent healing of the ligaments and tunica in an unstretched state. Hanging each day (or every 12 hours or even more often as some do) will slowly, over time, works on those fibers which are the tightest, breaking them down without breaking all the fibers (rupture). Each session breaks down the next set of tightest fibers, etc., etc. If you rest, those fibers may heal, and when they do heal you will have to apply more weight to re-stretch them as they will reform in a stronger state.