Usually takes me right at 16 hours from fire start to end of the cook for 4 butts in the cooker, assuming I don't foil 'em during cooking. I HAVE cooked a good pullable butt in 8-9 hours without foil, when I went to Paul Kirk's pitmaster class. We butterflied them, leaving the bone in. I wouldn't have thought I could do one that quickly at regular cooker temps, but we did.