I've been putting on a fairly large (~300 guests) 4th of July party with a group of friends for the last 29 years. I've been cooking all my life, but only started smoking about 15 years ago. This weekend was a little hectic due to the weather forcing us to move the picnic up a day from Monday to Sunday, but we pulled it off.
Anyways, this was the first year I made brisket for the party. I've done my share of briskets over the years, but never this much at once. I had 35# total across the three briskets. They were slightly wider/longer than my smoker (Masterbuilt 30" propane - modified a bit), so I had to cut them all in two. I ended up with had 3 large 8-10# slabs and 3 smaller 3-4# pieces. All prep was done on the whole slabs though. I didn't trim any of the fat.
I rubbed them all with Rudy's BBQ rub friday night around midnight, foiled, and placed in the fridge overnight. Saturday I rubbed them a second time around 6PM and refoiled them. Sunday morning I pulled them from the fridge around 3AM and rubbed them one more time, refoiled them, and let them come up to room temperature until they went on the smoker at 5am. They all went on fat side up and I didn't flip them during cooking.
I ran the smoker at 225F with mesquite in the chip tray. I only checked the temp in the interim once around 2PM to make sure they hadn't gotten away from me and it was around 150-170F on the large slabs. The slab at the top of the box was the hottest and the lowest the coolest, so I switched those two slabs around. I pulled them around 4PM with an internal temp of 190F for all three, foiled them and let them rest at room temperature for an hour until slicing.
The smaller cuts I didn't pay much mind to given they'd just be served as snacks to friends and passers by that were interested in what was going on. There was a significant amount of bark given their size and the fact they lost a not insignificant amount of weight.
Finished large slabs.
Apologize for the lack of "action" shots before and during the cook. They turned out extremely tender and moist, but arguably a little too peppery. I probably would have rubbed them one less time, but wouldn't have changed anything else.