I assume you did just a flat, based on the weight. I have found that flats cook so fast using the hot-n-fast method, they do not render as well as a slower cook. I am still trying to figure out doing a flat only cook. The last one I did was the closest to being the way I would like so far. I did not foil and really paid attention to the final half hour or so. I did not do temperature other than to tell when to start probing. Once it felt pretty soft, not as easy to probe as a slower cook, I pulled, panned and foiled. Then put back onto cooker as it cooled, coals going out. After 45 mins, pulled it out and sliced. It was better.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."