When you have the chance to read through more of the search on butts,you'll see my $0.2 many times.
First, check the temp your cooker shelf actually runs.
With experience,you'll pick your cook temp,for when the finishing might suit you.
Check the boil and freeze points on your therm.
Cookshack may recommend running the therm wire down the vent hole, but I can't remember.
If I have several wires running,for some strange reason,I arrange them on the door side,so I can maybe guess which is which and close the door.
On my small CS,I liked to buy two packs around 15-16 lbs,which is how the market receives them.
If only cookin one,I like my shelf to average around 235º.
A full cooker,around 225º.
If cooking several,I put the probe in the smallest.
It has a chance to finish first.
Remember that low and slow bbq is not linear for weight X temp= finishing time.
You are rendering fat,and breaking down collagen.
Thus, a 1/4 inch pork steak cut from the butt,fried a minute on each side in a 375º skillet, would be DONE,but not pullable.
Thus, it could take the same number of hours for four lbs to render and come tender,as eight.
The traditional CS cooks very moist,so I've not found pans of liquid to be helpful.
I pack as much rub and sugar on a butt,as it will hold,
a couple hours before the cook.
I might? open the cooker,around the 7-8 hr mark,on Big 8-10 butts.
I see if they need to be rearraged,or flipped over.Sometimes flipping keeps them from breaking.
If had had a spritzer of apple juice,I might? give them a squirt for flavor.
My personal experience has been that low temps,with a SINGLE big butt,in a Smokette,will plateau about 192º and be plenty pullable.
I like to get mine done several hrs early and foil,maybe with a spritz of apple juice,or some of Smokin's vinegar sauce.
Cooler for several hrs,and pull just before serving.I never worry how long they are in the hotbox,as long as they are temp safe.
As an example, Ribdog and I put a large case of 7 to an eight lb butt in Sat night, about 6-6:30PM around 225º.
They came done about 6:30-7:30 AM.
We double foiled them,into a cooler,and about 6:30 PM Barbara and drbbq pulled them.
They were still too hot to touch.
They were close to perfect.At least 3-4 hrs resting is a great thing.
When we pull our butts,we like to add a little more rub and some AJ,or Smokin's Vinegar Sauce,mixed in to taste.
Give 'em a couple sauces,on the side,to try on their own.
Once you've run your cooker a few times,and taken good notes,you'll know pretty much within minutes when things will happen.[on many common items]
Check your therm, about every cook,and then use your experience to guide what you are trying to accomplish.
Don't be opening the door and playing with the meat,although a quick glance won't kill you.
Well,I'll get off of here,before someone accuses me of makin' a Smokin' post.