I plan for my brisket to about 20 to 24 hours to cook. I get the rub on them the day before they go in the smoker, and put them in big ziplock bags in the fridge I think the term for this is a dry brine. The next morning I load the wood chunks, and briskets into the smoker, and then turn on the smoker. I set the smoker temp to 200 degrees. I want to get as much smoke on them as I can before the briskets hit an internal temp of 140 degrees. Once the IT is 140 degrees, I bump the temp up to 250 degrees and do not add anymore wood. The briskets are usually at 175 to 180 degrees IT when it is bed time. I turn the smoker temp down to 200 degrees and get a night's sleep. The next morning I turn the smoker temp up to 275, and wait for the IT to hit 195. I then start doing the toothpick probe method. Use a toothpick, or skewer to probe the brisket, and when the toothpick goes in like it would go into soft butter, the brisket is done The brisket should almost wobble like Jello. Some are done at 195 degrees, some at 200, and some at 205 or 210. Take them out and wrap them first in foil, and then an old towel, and put them in an insulated camp cooler. I also plan for the briskets to be in the cooler for up to 4 hours. This way if the briskets finish a little or a little late, they may spend 4 and half hours in the cooler, or 3 and half hours. I have done this method for about 15 years now, and even well sorted out choice grade briskets come out moist and melt in your mouth. Brisket is strange. When I see words like dry, or chewy, the brisket is usually under cooked.