First brisket flat I didn't butcher, hit 203 internal after 11 hours

Been cutting and wrapping for other folks for about 4 years, but my own smoker attempts were rough. Last Saturday I finally let a whole packer flat ride low and slow at 225 on my offset, wrapped in butcher paper at 165, pulled it when the probe slid in like warm butter around 203. Came out juicy enough that my neighbor asked if I bought it from a BBQ joint downtown. The lesson I learned was about resting, I used to slice right away and juice went everywhere. Letting it sit in a cooler for 90 minutes made all the difference. Anyone else have a cut that finally clicked after you changed one small step, or am I the last guy to figure this out?