Here's the thing: I make a rule of smoking VERY slowly, stretching out most of my bowls, mostly medium sized ,to an hour long, off of one light (after the initial charge). I sip my smoke, I am not a puffer. Maybe I puff to get a "dead" pipe going again so I don't have to re-light, but that's the exception. I am a tamper, and judiciously use this instrument all the way down the bowl. I notice bowls getting hot mostly, if not exclusively, with ribbon tobacco, which admittedly make up only about 20 - 25% of my tobaccos.
It usually happens in the bottom half, in fact, right after the halfway point. I often wonder if it's because I try to pack too much tobacco into the pipe to get the most smoking time. With my flakes, this is never a problem, or if it is, very rarely. (overheating, that is).
In writing this I come upon another question, that regarding ash. When smoking a tall bowl, like a poker or tall billiard, should you dump some of the top ash? Usually I don't and just ride it out, but I've noticed lately that with some new TALL, SKINNY bowls (Eltang poker, for instance) I've acquired it seems like there gets to be too much ash build-up with some tobaccos to allow the embers underneath to keep smoldering at a steady, controllable rate.
I appreciate all the help in resolving this vexing problem that pops up every once in awhile, seemingly when I am not altering my normal smoking routine at all when I get a nice, long cool smoke.