Ok, trying my first Pork Butt today on the smoker.....

I'm a big confused .... to Wrap or Not to Wrap ....

Some online recipes do low and slow all the way for 8 to 10 hours. (225 Degrees)
Some do low and slow (225) for the first half and then turn it up for the last half (250 or 275)
Some wrap in Tin Foil or Parchment Paper for the the later higher.
Some wrap AFTER cooking ....

What is the vote here?

(also, what gets the crispy crust on the roast .... the touch of dark to black on the outside? IS that what the wrapping is for?)