I think a norm that makes you lose your level is less useful than a norm that actively encourages you to keep it. For example, each month I briefly attempt to better at the "Self Control" skill. I've successfully done it once a few months ago. Since then I don't think I've done the full 8 days.

I don't want to be able to say "I am capable of working solidly in 2 hour chunks 8 times a month," I want to actually have done that, on a continuous basis (and frankly I want to do better than eight 2 hour chunks, but from my own experience I think it's a pretty decent level 1 achievement, embarassing as that may be.)