I work between 32 and 35 hours each week. I think about Treehouse a ton more (if I'm not asleep I've probably thought about Treehouse in the past couple of minutes), and answer email from time to time, but I don't know anyone who doesn't do that, and I usually get mean looks from my wife when I spend much time outside of my normal work hours answering email or playing around with code.
In general I don't think people on our team work more than 32-35 hours or so. One exception is our support team, and that's something we're working on remedying.