Two schools, both completely respectable in my opinion. I'm of the school that scoops out the ash, then wipes out the bowl with a paper towel or paper napkin. I don't build cake. I just maintain a thin layer of carbon, and this keeps pipes happy for many decades and tastes just as good (or better to me). But the cake building school is a long honored institution and pleases many. Just don't be like some of the estate pipe owners who build so much cake there is barely room for tobacco; that's overdoing it.
