Somehow when you are slow cooking or smoking large pieces of meat something called a stall can happen. The meat stops cooking. You can read about it here. This can last for a long time and while this guy whose link I have provided here seems to understand it, apparently no one else does but they all know how to solve it: the Texas Crutch.
Real die hard pit masters scoff at this method. But not being a pit master of any sort, much less Die Hard. (My parents loved that movie). I use the Texas Crutch to excellent effect.
And the city of Milwaukee recycles aluminum foil.