I set Gillette adjustable at 6 for a couple of years, because I thought that higher numbers were for tougher beards (my SO likens my whiskers to razor wire), but eventually settled on 4 about 6 months ago, when I experimented after realizing I was not getting close enough shaves. Haven't budged the adjsutment since. Oddly, today I put in a Walgreen's blade (pretty sure it's a rebranded American Personna), in place of a feather (ran out of them, dammit), and thought I would have to adjust up or down -- but I got a damn nice, close shave without adjusting! I think it's more likely technique, rather than adjustment (or even the blade), that's making all the difference.