Briskets come in a wide variety of sizes, from a small one pound size common in the supermarket, to massive fourteen pounders meant to spend an entire day in a smoker; in this recipe we call for about a three pound brisket. Feel free to use whatever size you need to feed everyone at your table. but be sure to adjust the cooking time accordingly. Having an in-oven probe thermometer will be a huge asset here, since being able to pull it out of the oven right at 185°F and letting it rest for a while will give your brisket the maximum amount of time at just the right temperature to melt the fat without overcooking. The key to a tender brisket is cooking it just long enough to allow the connective tissue to breakdown, without leaving it dry and tough.
Also, when making the whiskey BBQ sauce, be sure to use a whiskey you would drink. The old adage about not cooking with something you wouldn't drink yourself isn't just for wine!