Despite being a pipeman for about 17 years now (started when I was 18, am now 35) I still have never been sure how far down to smoke the bowl...when breaking in a new pipe I half-fill and try to smoke to the bottom (or until it tastes unpleasant and I feel woozy), but for a broken-in pipe I always find I have to knock it out while there is still some unburnt tobacco in the bottom.....what do other people do? Smoke until there is only ash? Stir up the dottle and relight to burn all the tobacco?