Well, I've learned 2 things so far about smoking pork...and yes, I'm still very green about smoking. As with most things, I read and read and read until I understand the concept of what I'm trying to achieve. It drives my wife nuts. In some of my studying, I learned that once a boston butt reaches 160*F, the pores start to close and it won't absorb much more smoke beyond that. So continuing to add chips and keep it smoking is a waste of chips and time. Depending on how long it takes to get the internal temp to the 160 mark (which varies as you know), is how long you should bother keeping it smoking. Remember that it's all about temperature and not much at all about time. 2nd is that I presoak the chips in water which make them last longer. Also keep in mind that just because it's not puffing smoke out the vent, doesn't mean the box isn't full of smoke. I learned that fairly quickly. I was adding chips when I didn't need to. Opening the door proved that when smoke came bellowing out...even though there was next to none coming from the open vent. 160* is also the same temperature I take it out and wrap it. After that, the smoker is really nothing more than an oven. So far, my methods have yielded some excellent smokey flavor without over cooking and drying out the meat. I read where a lot of people who smoke on a pellet smoker or grill will actually remove the butt from the smoker around 160*, wrap it and finish it off in their kitchen oven.