I usually just brine for 24-48 hours depending on schedule. I will say the longer brine has better flavor, moisture is about the same.
Here's what I do to brine a 8# deboned butt.
Mix 1/4 cup kosher salt, 1.5 tsp cure #1, 1/4 cup memphis dust rub, and 1/2 cup water and heat in microwave to dissolve dry ingredients. Then add 2 cans frozen apple juice concentrate to cool mix
I spread a light coating of memphis dust into cavity and on the butt then tie butt with butchers twine to compact the butt so it will cook evenly.
Then I put the butt into a 2 gallon ziplock bag and the pour in the liquid mix (adding enough water to make sure the butt is covered after all the air is expelled from bag).
Put into fridge and turn butt every 3-4 hours till ready to smoke.