My uncle said to stop opening the lid every 20 minutes, and he was right

My uncle Ray ran a pit in Lockhart for about 15 years and he told me back when I got my first offset that if I kept peeking at the brisket it would dry out. I ignored him for two summers and kept spritzing and checking every 20 minutes on a 225 degree cook, and my flats always came out like shoe leather. Finally gave in and left the lid shut for 6 hours straight on a 12 pound packer, just wrapped it at 165, and it was the first one that actually jiggled right. Now I just watch the stack temp and trust the process, way less stress too. Anybody else have a stubborn streak that cost them a bunch of good meat before they listened?