I trim all external fat but 1/8" of the fat cap. There is a large chunk of fat between the point and flat, I take all of that out. I also trim the thin edges as I dislike how they cook. I tend to square the sides of the brisket up a bit. I peel any silverskin left on the underside of the flat as well. So yes, a lot of waste comes off a packer in my cooks. Easily 2 and sometimes more than 3 pounds.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."