The thoughts about finishing temp for shoulders/butts come from the years with the small Cookshacks.
I found that for timing purposes,I might want to start at 200º,the evening before feeding,then maybe kick up to 225º in the morning.Around 186º-187º,I'd get another long plateau,and then it would move on up and hang around 192º-193º.If I checked it at that temp,it would be falling apart on the rack.
Yep,it was real tender-but overcooked.The experienced pork cooks here will know the mouth feel/dryness of overcooked.
Thus,there are times it is worth opening the door and squeezing the butt,or twisting the bone-even though we aren't reading our desired higher internal temp.
Just a thought.