I have a couple of Olympus OM's that I use all the time, and they're always kept in a bag. Just a habit I got into long ago, when I realized I couldn't stand a camera hanging around my neck. Plus, the protection, etc.
Anyway, sometimes I forget to turn the camera off, (for several days at a time), and it doesn't seem to affect battery life.
So, my question is, if the light meter has nothing to meter, is there little or no battery drain?