well, i have never shaved my armpits, but about 2 weeks before and through the season i do trim it down a bit so i can wash all the deodorant smell out(if you ever notice you still smell like your deodorant even after a shower). Reason number two is the no scent deodorant tends to clump a bit, a little less hair=less clumps. this is trimming it down, not shaving, that is a bit much lol.

Shane