Time and temperature are just general guides. Probe for tenderness before you wrap in towels or wadded up newspaper and put in a cooler. The probe should go in easily, like a hot knife in butter is the saying. Remember that each brisket will take its own good time to get to probe tender.
Jim - Another transplanted Texan
Former KCBS CBJ
Large and Medium Big Green Eggs , Black 18.5" WSM, Blue Weber Performer - Stainless, Green Weber OTG Kettle , Brinkmann SnP Pro, and a Stainless UDS. One retired Portable Kitchen grill.
Red Thermapen, Maverick ET-732, EdgePro Apex Sharpener.
Avatar is the original 1951 Weber Kettle