I'm probably cleaning mine twice a week. I'm using a Piranha Float Magnetic Glass Cleaner by Algae Free (which I absolutely LOVE). I was just curious as to the average time most other people were doing it since I wasn't sure whether or not twice a week was unusual. I do it at the first sign of film when viewed from the side (and, to answer another question posted above, I clean all three sides of my tank).
I just wanted to make sure that it wasn't due to my light cycle, or something like that. But it sounds as though I'm pretty much in the same boat as all of you. So thanks for the feedback!