The best burnt ends I've had are competition BE's. All we do it cook the whole packer until the flat is done. Then we remove the point from the flat, try and take off all the big outside layer of fat, cube into about 1.5" cubes, lightly sauce, toss in a foil pan and back on the smoker.
We let them render out for at least a couple more hours, checking once in a while. Lightly sauce about every hour to carmelize and get nice and chewy.
Once they're fork tender, they're good to go.
They should be nice and meaty with a sticky, gooey chew to the outside. Mely in your mouth tender, but still beefy. We don't re-rub them at all. I"ve done that but they end up real salty (I guess depending on the rub).
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team