I did a 26 lb chuck roll couple of months ago. When the temp started looking like it needed fuel, after about 14 hrs, I opened the door and tossed in 30 briquettes after a couple of hours I tossed in 30 more. If I were to do it again I would put the first 30 in at 12 hrs to keep the temp up a up a little sooner, I also stirred the coals at the 12 hr mark so most of the ash dropped into the bottom and gave the fire a breath of fresh air.