Yeah, that is the general rule. I just cooked my first brisket flat and it was right at 1.5 hrs per pound. My only tip....start early . That way u can be patient with the meat, track how the meat warms up, and take your time getting to your target IT. Mine was hard at 190 and almost like butter at 200. If u finish a little early you can pull it off the smoker, wrap it in foil, wrap it in a couple towels and let it rest in a cooler. Mine only dropped 8 degrees in one hour while in the cooler, so u can see that they can rest for a little while. Good luck!