For mixing meat for sausages to be put into casings, I usually go for 1.3% or less per pound of meat. The casings seem to retain a lot of salt even if well rinsed, plus if you’re using spice “mixes” there is usually added salt in those as well, such as “chili powder”, etc. The salt content can really add up and become a killer. I’m all for low-sodium, but there is a minimum that needs to be in there for the overall flavor.