Pork butts can't tell time!
Seriously...take your watch off!!!....Use a thermometer to determine when they are done...
Sliceable & Pullable 185*
As you move towards 200* and over the meat may start to become "mushy" with almost no resistence to the tooth...Personally, being a carnivore, I like tender with just a little resistence...In fact I pay extra for it.
If you are up against a service time...I always allow myself anywhere between 1 1/4 to 1 1/2 hours per pound....