Normally I don’t worry about how shinny the brass is but after I started using One Shot some of the finished rounds seemed sticky after reloading. They did sit about 9 months in the basement. So I started tumbling the finished rounds for about 15 minutes in fine ground corncob and they come out real shinny now, and no more stickiness from sitting is a 5 gallon bucket in the basement. I typically don’t use polish because it just seems to gum up the works and create lots of dust, even using the dryer sheets. BTW, WD-40 seems to cut all the crud at the bottom of the tumbler bowl fairly quick and did not appear to damage the plastic of the tumbler, it’s a small Dillon.
Joe