I've always experimented with cooking/grilling/smoking. I can't stop. Heck, I've got a pizza dough experiment cold fermenting in the fridge right now, but back to butts.
I've been the main cook in the house for decades. When I wanted pulled pork, I'd oven roast the meat uncovered at 350F for three hours, then cover it and roast it for another 2-4 hours at 350F until it was tender. I was never a fan of the slow cooker. There are lots of recipes online that have you foil right from the start when oven roasting. I've done it, and it works too.
When I first started smoking I always foiled butts at the stall because it was similar to how I'd oven roasted them for decades. At the time I was not a big fan of bark. When they hit the stall, I foiled. I used a variety of chamber temps.
After I got familiar with my smoker, I tried bumping the foil temp up to 180F internal temp. It gave a slightly firmer bark and I liked it. That was my go-to for quite a while.
The first time I let it go unfoiled until it was done, 8/24/2014, I kept the smoker at 225F the whole time until IT reached 205F and it was probe tender. An 8 lb butt took 17.2 hours and it was AWESOME!
Then I switched to hot n fast, 275-325F, no foil. Great bark, juicy meat, target temp and probe tenderness reached in an hour per pound. I was working then and often took PP to work or block parties for potlucks so the hot n fast worked great. I still use hot n fast if pressed for time.
Once I quit working, I switched it up again. 225F overnight, then crank it up to 275+ in the morning as the meat is coming out of the stall. Great bark, juicy meat, probe tender.
I now rely on probe tenderness to tell me when it's done. Because I use a thermometer to probe for tenderness, I get the IT of the meat too, but regardless what the IT tells me, how that probe slides into the meat tells me if it's done or not.