For what it's worth, I've learned 2 things about brisket for Family and Friend cooks.
1. Go with a Choice or above grade packer brisket or don't bother.
2. It's done when it's done. Temp is and indicator but not a gauge.
Weber WSM, Weber GA, Weber Spirit S-320
Charbroil Oilless Turkey Fryer
Wife LuzziAnn 1956 model.
Maverick ET-732, Superfast LSU Purple Thermapen & ThermaPop, Party Q