I bought a 5 lb brisket flat, a little fat on the outside, moderately marbled.
I smoked until 140, and noticed that the brisket seemed to be plateauing at this point. I decided to assume this to be equivalent to a bigger brisket stalling at 160, so I decided to foil at 140 as an experiment. I took it to 200, and pulled it to a cooler, resting it for 1.5 hours. It was heavenly; I am new at this, and dried out a larger brisket beforehand, but now understand why people like brisket.
I used the BRITU rub, sprinkled lightly, and then sprinkled a light coat of McCormick's steak seasoning on top for good measure.
I will no longer shy away from the little briskets and will use this method in the future, as it is nice not to have to buy a half a steer for just my wife and me!
Robbo

That's how I do small briskets also but I let the brisket tell me when it's ready. I start checking at about 180*.

What is the BRITU rub? Thanks

BRITU rub is part of an overall process,and is often found too salty when used as a stand alone.

This is from Mike Scrutchfield,graciously posted by ChrisA on the Virtual Bullet forum.

Mike's Brisket approach can be found this week on the open,or recipe forum.

BTW,IMO, the weight to internal temp isn't linear.

I.E.

You can fry a 1/2 inch thick slice of brisket to 140º internal in about one minute /side,and still not be able to cut it with a knife.
Collagen breaks down with temp,over time.

Many cooks feel that the longer it is in the plateau,the better it breaks down collagen and renders fat.

Just my $0.02