Any lessons learned from using OKRs?

I helped a client in 2016 to introduce OKRs.
First 2 years it was an approach for a department of 10, bottom up with quarterly and annual OKR per member, reflecting on the departments goals. OKRs were shared on a whiteboard across the team.
2018 they extended it to the whole division, 120 people, 4 departments, it was top down based on a management workshop, with bi-monthly 'reviews' and it failed for trying to mix with command & control culture. Now 2019 they go back to quarterly/annual and no reviews but retrospectives.

My take-aways:
- Command&Control vs. bottom up culture - OKRs go best with latter
- OKRs are best defined and committed by each employee, not top down
- OKRs are not personal targets for HR purposes (OKR = business progress, personal targets = improved capabilities)
- department OKR and management staff OKR not the same
- visibility of OKRs - not to everyone, but within team (staff may not set good individual challenges if publicised, German laws prohibit such h anyhow)
- team OKR on poster, signed
- OKR bottom up vs. top down (road map)
- frequency of re-checks quarterly / annually
- purpose as prerequisite for OKRs

Read "Measure what Matters" by John Doerr. One correction to the original post is that it originated from Andy Grove at Intel and was adopted by Page and Brin at Google.

Kiron