It's kinda freaky, Steve, how FAST some large cuts of meat climb, initially! I say initially, because that WILL change! While we've all gone through the "panic mode" of thinking our 13 lb brisket is going to be done in 4 HOURS!, it NEVER will. Even though that voice in your head, if you've been studying our forum, tells you it won't, you still can't believe your eyes! Trust us, your brisket will not be done in less than 13 hours. Relax, and enjoy a cold beverage (or two)... you've got time on your hands!
I agree with Walt - 2 hrs/lb on brisket is way too long. I always average 1 to 1.25 hrs/lb. But, if it's done early, you can double-wrap in foil, let the smoker cool down below 140, and put it back in there, set to 140. You can "hold" for a long time, at that food-safe temp!