I pump mine up before every ride, but I though I was being neurotic and didn't want to make pooks feel intimidated...once a week is probably sufficient for most people.

I'm glad I'm not the only neurotic tire pressure person out there. I went four years without a flat...til this summer when I had a bum tire on my road bike and the sidewall burst miles from anywhere. And of course, as you know, flats come in threes, so I had two more. Now I'm safe, for the time being.