I normally remove the brisket once it reaches 185 degrees unless I am going to pull it, in which case I will let it get as high as 200 degrees. Sometimes, during an all night brisket smoke I will only let it reach 180 or so and will then wrap it in foil and then in several thick towels and place it in a cooler with several pillows to hold it until we are ready to eat. It will maintain temperature for several hours this way and be even more tender when you take it out.
Around 7:15 the next morning and many marinades and flips later the brisket has reached 151 degrees and reached a plateau. Anyone who has smoked meat has no doubt experienced this strange phenomenon. The meat reaches a certain temperature and gets stuck at that temperature for sometimes hours on end. This happens to me every time I do an all night brisket smoke as well as when I am smoking ribs or chicken or whatever else I might happen to be smoking.