Halves are the only boxes worth doing, but only barely. Used to get two boxes a week but I stopped about a year ago. I think my average was 1-4 silver halves (often the '65-70 40%, but occasionally pre-65 90%) per two-box trip. It's not really worth it, but it's fun. A couple times I got bonanza boxes that had 8+ silver halves in 'em.