Muhahaha, posting during work hours on my 20% free time. ;) Most people do their 20% projects as solo things rather than team-based. It's a pretty flexible concept though. Some people get on a project for a long time where they have to work hard; then you might have to save up the 20% time for a little while. And there are parts of Google where people are working hard are the time. I'm not sure how to help make sure that every engineer gets/takes their 20% time, but I think it's good for every person if they get the chance to tinker. Several 20% ideas have turned into things that you see on the main Google site (esp. projects on Labs).