Originally, I was under the impression that FTC would improve the end product. Like resting a steak, but taken to the next level. I no longer believe that anymore. I think that it's a dubious workaround for finishing your cook early. I figured out the maverick trick to monitor cooler temps a while back and would rest briskets in a nice snuggle of towels for 4 or 5 hours knowing what temp it was at. Sounds ideal, does it not?
What I found was that the chunk I would cut off the flat to test the brisket was much better than what came out after a long FTC. It looked to me like I had took the rendering too far. Nearly all the intramuscular fat was gone. Still tender, but it gave the point a somewhat spongy appearance due to the voids. Flat was noticeably drier. I also took note of the significant quantity of oil, rub, and juices that would accumulate in the unwrapped foil. The end product while still good to my guests, was disappointing to me when compared to my previous sample.
Then one time I hit my brisket finish time perfectly and set the chunk of meat on a cutting board and let it rest at ambient temp and sliced it after about 45min. I didn't lose nearly as much oil and juices, the bark (I like the bark on mine firm, but easy to slice and chew) was in better condition by not being disturbed by the foil. And the slices of brisket looked like they should with slight pockets of glistening fat when pulled apart.
I haven't figured out timing yet so my new brisket policy is, "it's ready, when it's ready."