Actually, about once a week or less (and then it's like no more than a couple of hours). I've been really busy with work lately because a co-worker (my brother) went on holidays so the rest of us have been picking up some shifts. It's not all that bad as we're now receiving big fat cheques but I haven't actually ran a game in about 3 weeks, besides the occasional 10 minute time killer moments playing THPS HD or something.
I usually try and play more. It's just that in my few days off I'd like to spend it with friends, go out and such.