As is often the case with BBQ, when smoking a pork butt the thermometer should be one tool that you use, but is not the be all and end all.
At Saddleback we like going by “feel” to be our final determining factor. You want the shoulder to feel “loose”. It should have a good amount of jiggle to it when touching it. When inserting your thermometer if it goes in with almost no effort, you know you’re getting close.
We typically smoke our shoulders around 250 degrees for 6-10 hours. We are looking for an internal temperature between 195-205. We know a shoulder is ready to come off when you can easily pull the bone out.