Please remember that the internal temp is only one guide of deciding when the brisket is done. Each piece of meat is different. I've had briskets finish as low as 188° and some I've had to take to 205° before they gave up and decided to become tender. Use the internal temp as a guide to let you know when it is getting close. The single best, for me, way to tell if a brisket is ready is to feel the resistance to a meat therm probe (or similar thin pointy object) going into and being pulled out of the flat. If it takes a bit of effort to poke and remove the probe it needs a bit more time. If it goes in and pulls out very easily, your golden. Also don't forget to let the brisket rest for a good while before slicing.