I just did my first packer and was a little confused on the subject. It was a 14.5 pounder. I think alot of folks get confused when the word Brisket is used. Many folks consider a "flat" as a brisket, while others consider a Packer (Flat and Point) as a brisket. Heck, many folks don't even know "packers" exist. You can't find them every where. Thankfully, that's not an issue in Nebraska or Texas.
Given that confusion, I think some folks operate under the impression that the "point" is the pointy end of the flat.
Given it was my first packer, I did the same thing you did. I monitored the temp in the point (the big thick fatty end. While I was very happy with my results, I felt my flat was just a tad dry for my taste. When I think of this logically, if you monitor the temp in the thickest part (point), naturally the thinnest part (flat) will be significantly warmer.
SO... the next one I do, I will monitor the flat. When the flat gets to temp, I'm going to separate the point and the flat, wrap and wait on the flat, cube the point for burnt ends and finish them in the cooker.
Just my experience....