I worked at Google from 2002-2007, and the dirty little secret is that there is no 20% time. It's 120% time. You work a full schedule, and if you want to put in extra hours for a side project go ahead. I explicitly asked to use 20%-time to work on a side project (i.e., literally take 1 day a week to work on it) and was refused.
20% time has always been a great marketing gimmick for Google. I remember interviewing candidates and mentioning it as a bonus to prospective candidates - most employees mentioned it as a bonus because we were inculcated into believing it was actually a bonus. It's much easier to see that it was never a real perk once you're outside the bubble.
replies(1):