The UDS is a fuel effecient beast!! 10 to 12 lbs of charcoal will burn 12-14 hrs, no need to add fuel or wood, 3-4 chunks will last as long as the burn!!
The drum is so air tight that you control the burn with your intakes, NOWHERE to leak air to fuel the fire so it burns as slowly as you allow it!
If you build, you will believe!!