First butts

Welcome to the forum.

Since you asked, I will say using foil on a pork butt is a waste. Foil is usually wasted on a brisket and is known as a Texas Crutch. Those times are not at all uncommon. Foiling will also soften your bark. Bark should not be soft. Good pulled pork should have bark.

The first answer would be that a cookshack is such a wet cooker that folks open the door on cooks, to let out moisture and help bark formation.

Cooks may use foil to speed the cook,if they are behind schedule.

Much like placing a lid on a pot, to braise/pot roast meats.

Pure stickburners may foil, to keep from oversmoking butts.

If you have a dry cooker ,that flows a lot of air,you may also sometimes foil.

A butt has lots of internal moisture,on its own,and is hard to dry out-unless you overcook to mush.

Just my $0.02
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