That's even a bit short. The median I listen to is probably around 12 hours, and the more popular series tend to be in the 20 to 30 hour range. Brandon Sanderson titles can hit in around 60 hours.
I usually read/listen to a lot of books, compared to most people, but not several hundred. And if you're reading Brandon Sanderson as part of that - wow! I'm envious :)
Listening at double speed makes a big difference.