This is the most important aspect.
The key factor that separates the good from the great is execution capability.
When you set targets, we set aspirational targets, that is, the targets are stretch in nature.
Even if you achieve 70% of the target, its good enough and that in itself is a great achievement.
An inherent aspect of the stretch target is that its entirely possible to fail to achieve even 50% of the target in some cases.
So, be prepared to fail.
If your organization is so concerned about driving “all green” metrics, I would say that you are not ready for OKR at all. Even if you try, you will fail.
So, organization culture plays a very important role in OKR.