Can someone give us a review how the 20% rule works/worked at Google? What I've read has always been second hand. Not directly from a Googler. I suspect that at

Can someone give us a review how the 20% rule works/worked at Google? What I've read has always been second hand. Not directly from a Googler. I suspect that at the very least the 20% gives high employees a way to decompress for a bit by working on projects they love rather than ones that they have to do.