I sat every day for about four years but finally stopped after my practice grew neurotic. I had no teacher. For the last ten years, I've been sitting very irregularly - sometimes as infrequently as once every six months.
Recently, I'm sitting much more frequently (almost every day). I've noticed something very odd.
I've drifted FAR from my original values in the last ten years. Some of those values were neurotic or problematic (I was very self-righteous, equated virtue with poverty, was very 'anti' a lot of things), but some of those values were very important. For instance, I'm currently in a lot of debt. I have a lot of material things I wouldn't have considered back in the day. Mostly though, I've just made a lot of choices that don't reflect the sort of understanding I once had.
There's not a lot of moral teaching in Zen (at least not compared to Theravada). Nonetheless, my experience is that daily sitting can keep one pretty on track in a lot of ways. Also, I've never been as happy as I was in those first two years of daily sitting.
Is it really true that one's mind can so easily become clouded without daily zazen?