Just did a 18lb on the weekend
Followed the Texas recipe with some minor tweaks
Iron wood650. Stalled 140-142f
Turned up to 230. Broke the stall, and finished the instructions from that point on at 230
19.5 hours plus 1.5 hours resting
Just for the educational piece, in case it wasn't a title typo;
"A whole brisket (know as a packer brisket) is not typically stocked at your neighborhood grocery store. Packers are large hunks of meat that the average hot-dog grill master will never cook in their entire lives. "