I think it depends on the team and your role in it. I worked at one of the Google X moonshots and never heard of this. There were a couple engineers from other

I think it depends on the team and your role in it. I worked at one of the Google X moonshots and never heard of this. There were a couple engineers from other teams that were donating one day a week to helping us, which is a similar 80/20 split. These 20% were somewhat common at Google, I believe, but it was never to take time off work.