Originally Posted by nozzleman
There will more opinions on these questions that you can shake a stick at. I personally don't foil in order to preserve that bark that you like. The brisket will power through the stall, it just takes a little longer, but I have the time. Once you get that good outer bark started it will seal in those precious juices. How often to probe, the more you open the door the slower it will cook, go at least an hour in between, longer depending how much temp change you are getting. I don't use sand or water in my smoker but then again I am not one that opens the door all the time and they act as heat sinks to aid in the recovery of your temps after opening the door. I usually try and cook around 225-230, and for a full packer it usually is in the range of 12-14 hours.Good Luck.
Agreed for the most part. One thing I'd point out is that there's a bit of a myth to "if you are looking your aren't cooking". The meat itself is very good wrt heat retention. Opening the door for a minute to check the brisket will drop the chamber temp a bit and that will take some time to recover, but really won't affect the overall cooking time that much as the brisket itself retains the heat.
FWIW, if you take this to a ridiculous extreme, like opening the door every 10 minutes and taking 5 minutes to test, yeah, that will definitely have an impact. Just have the probe in hand, quickly open the door, poke the brisket one or two times then close the door.
It's kind of like your refrigerator. A gallon of milk is sitting there are about 38 degrees. If you open the door and look in the fridge for a minute and then close the door, that temp of the milk isn't going to immediately spike up and take a noticeable amount of time to recover. It will still be at 38 degrees.