I take off more days than I'd like. Today for example, there's lots of rain. I have a 37 mile commute and don't ride in the rain. I've got no fenders, and don't want them. The additional maintenance and cleaning my bike requires, as well as my general displeasure of riding in the rain keeps me off the bike. It makes me more eager to ride when it's sunny out.

On a good week I'd be able to commute 4 days a week. On a bad week maybe 2 times per week.

Either way I try not to fret about it. I find that if I start to worry about this stuff, or take it dead serious, that I will burn out.