Nice! and your lessons are very much aligned to mine as well.

- Yes, shared OKRs are necessary to align teams and departments (one of the major benefits to them in my experience) and a way to help ensure strategies aren't set in isolation.

- Collaboration on goals/objectives/strategies are a must. They're not isolated, they're connected therefore needing cross-team/department collaboration. As you say in lesson (3) they are a cross-functional thing!

- And since they are interconnected, setting them in a silo without the consideration/alignment to other goals/strategies is dangerous. The examples that you gave in (2) are a good example of the benefit of having competing KRs, like growing client base without being at the cost of retention. By having bespoke objectives with competing tension between KRs you help maintain balance - same way I describe the constellation of strategies, they should be 'pulling' each other - i.e. retention vs growth.

Great lessons and thanks for sharing!