Used a lot of pork butt, but would like to find other ways.
Our local IGA grocer has a meat dept where they actually cut carcasses. They will save and sell the trimmed fat.
It’s a better way, IMO, because I can weigh the meat and fat to hit the % fat I want in a product.
Pork butt (shoulder) makes a good sausage by itself, but using that in the sausage grind does not allow accurate fat calculations.
YMMV, as always.