I don't know that "common" is necessarily descriptive, from what I've observed here the norm seems to be around 15-20mi round trip. That said, there are more than a few here doing the distance you're contemplating.

On the longer commutes, endurance is really the key. If you've been riding distances for a while you can probably knock it out easily, the key will be the third or 4th day. I've found personally that it's really dependent on how well I sleep and how healthy I eat. My norm I don't sleep a lot of hours to begin with, so throwing that even shorter has a direct effect. There are some weeks by Friday I'm looking to ride a century on a weekend, and others by Friday I don't want to even look at the bike much less ride.

There's also a certain amount of psychology involved. It's really easy on a long commute (or a short one for that matter) to find a reason to bail, and I won't pretend that sometimes I have to make myself get on the bike. I'm always glad I did, and if I don't I regret it all day. I also notice a definitive increase in my alertness level between riding and not riding. If I don't ride I'm like a slug.

Just some observations