I really hate to disagree with you Drew , but the exhaust must be left open fully the whole cook. I do however agree to the shut down , that and the ability to keep Rain/Water out of the inside of the Smoker (which may damage it) .
The beginning of a cook should include a patient wait for the fuel to get settled in the unit (to temp. ,steady) then add the food. ( read my Stickburning101) and as mentioned... Practice
Take a Weekend or two to learn your Smoker , the process of lighting , getting to heat, maintaining heat , temp. fluctuations and hot spots , color of the Smoke produced , time for each process to occur , etc. A BBQ Log is a great tool for learning and keeping all your BBQ cooks and how they went , processes for correcting you mistakes , how you did "the good job " cook , recipes , and any other info. you might want for posterity.
Have fun and . . .