I think with the liver, once you release a certain amount of stones, that you often need a series of flushes to set-up the next cleanse and move the stones into a position where they can be released by the next flush. That's why as time goes by I think you need to do five flushes or so just to get that one successful flush. I would love to see inside my liver and see how the stones move and whether they take up awkward positions. It feels really satisfying when I get rid of stones after a few stoneless flushes because I knowed I've won the battle with them hiding in my liver ;^)
I know lifestyle issues are seen as a big issue regarding stone re-formation but I think the power of a good cleanse vastly outweighs the rate in which stones form. I remember LisaG coming up with interesting statistics which re-inforce that view.