I just wish to express a small preference when using a rocket mass heater. Usually, all the wood I burn is 15 or 16 inch stuff. The standard size for firewood. But once in a while there is an end piece for a log that is something like 10 or 12 inches. I like to keep that shorter stuff handy so if there is a bed of coals, but I want the fire to run longer, I can throw the short stuff in and the wood does not protrude above the wood feed and lead to problems.
I like this so much, I think it could be wise to actually try to make more stubby sticks when carving up the tree.