Nice looking butt!
I've found the point at which the stall hits, and duration of said stall, a total crap shoot - depending on the cut of meat. Also, I've never had success with the "x-hours per pound" calculation. Here's what I'm talking about: I usually see the stall (in a butt) somewhere around 165-170. This weekend, I had a 8.75 pounder not stall until 185! I was freaking out! But, it finally hit, and the temp backed down a few degrees, and sat there for the next 4 1/2 hours. Another time, I put an 8 lb butt in for an overnight cook @ 11 pm (thinking it would be done for lunch)....wrong! It was sitting at 198 at 8 am in the morning! Ended up holding it in the smoker @ 140 for 4 hours before serving (which works great, btw).
So, what I've learned is there is no real "formula," or consistency for large cuts. When you go off of internal temp (which most of us do), there are a lot of variables that effect the time; ambient temp, cut of meat, amount of fat/connective tissue, humidity, etc... just to name a few. I guess that's what both excites me, and frustrates me, about this hobby! Of course, pork butts are really forgiving large cuts, briskets not so much. There's really no easy solution. Things like ribs, though, you can pretty much "dial-in" with a time that's going to be pretty consistent.