Smoked a bowl of ILTOBC last night. It was perfect a full 2 odd hours.
My setup was a small phunnel, KM Americana, narbish, cold water in the base. 2 CH nats on the bowl to start, about 3/4 on the bowl across from each other. 20 odd minutes, ashed, flipped and rotated the CH nats. 20 minutes later, add wind cover. Once those died, time for a new set of coals.
You really don't need more than 2 coals at a time, at least using coconaras or ch nats. I didn't even have to purge once during the session.