That request seems very normal to me, maybe a little light on all fronts in fact.
On a packer brisket from the package...assuming a 12 to 15 pound packer:
1.5 to 2 pounds lost to trim
35% weight lost during cooking
So, a 14 pound brisket will yield 7-8 pounds of cooked meat. Three servings per pound, you are looking at 20 to 24 servings per raw 14 pound packer.
me: I don't drink anymore
Yelonutz: me either, but, then again, I don't drink any less