Ya i go with DDave there, 185-190 in 2 hrs, if your smoker temp is set at 500 maby but no way on that.
Ive seen to many times that a brisket put on the scale as a nascar race, who can do it the fastest, i used th creamator in the morg next door and i did my brisket in 5 min 53 sec at 1200 deg.
my best briskets is a good heavy rub on it and put it in the smoker at 205-210 range and leave it for 18+ hrs, iv had briskets hit 200 deg at 20 to 22 hrs at a temp of 200-210 range.
knowing your rubs,sauces, and such will teach you alot.