A buddy of mine built his UDS with spare stuff around the house and 18 dollars. The day he seasoned it he filled the basket with one bag of Kingsford Blue. After 4 hours he turned down the heat to 230 and did some ribs. After the Ribs were done he put a shoulder on it. About midnight with the shoulder done, he went to bed and in the morning it was still at 230, so he made some fatties. He came to work the next day bragging that the UDS went over 22 hours before it started dropping off, that story, and lunch for the crew.
Me? I've never gone more than 16 hours and I had coals left over.
SAUCED HOG BBQ / KCBS CBJ #60733