The policy still exists (it is still encouraged, me & my coworkers used it in the last ~2 years).
The "120%" issue is up to individual / manager (like many things at Google), I just took Fridays off of my main project, other people have different approaches.
Whether doing 20% impacts performance / promotion - it again depends on the individual and their level, two data points:
- I used 20% to start a team / role transfer, ended up on a very interesting project & team which helped my career growth
- one of my coworkers used 20% to start & maintain an internal feature of a large product that directly helped his promotion case
so I think 20% is great for Google and its employees (when applied wisely).
Whether doing 20% impacts performance / promotion - it again depends on the individual and their level, two data points:
- I used 20% to start a team / role transfer, ended up on a very interesting project & team which helped my career growth
- one of my coworkers used 20% to start & maintain an internal feature of a large product that directly helped his promotion case
so I think 20% is great for Google and its employees (when applied wisely).