I do it but I've been wondering the same. The problem I think is when you use the same media/tumbler that you clean dirty brass with, which I was doing for a while. Now I only tumble loaded rounds in my small frankford arsenal tumbler, and leave my brass cleaning to the dillon.
My lead level this year was like a 22, only a few down from 26 last year. Was not happy about that, so been trying to be extra careful this year.