Single-course grind is what I do. I do not add extra fat from beef or pork unless I am making sausage; then I sometimes do 2 coarse grinds to mix everything up. I'll add fat to the burger when I'm cooking if needed.
single course grind or double grind for burger. Add anywhere from 10-30% (heavier percentages for sausage). Been testing it out each year and we're finally starting to hone in on what we like the best. Wanting to start doing some summer sausage recipes