Cromag, hello and how are you?
A Rick will get you appox. 4 smokes of 10-12hrs. depending if you are sealed up or not. This is the main reason I choose to not open the lid as I smoke.
I'll go back to a theory I have , leaving the lid shut will hold more of the heat,moisture and smoke thus making your cook more efficient and quicker.
Use your Nose , Eyes and Ears to keep track of your cook. You can see the Blue smoke , smell foul odors in the smoke and hear poping and crackling of the wood as it burns actively , instead of giving you good smoke you want (driving the heat up and burning or ruining your meal).
Like a house you want to heat-up , open the door and there it goes . . .
Just sayin' , keep the smoke Blue and as always . . .