OKRs should be achievable and valuable. It is acceptable if they are hard, but that is an unfortunate source of risk and it is better if they are easy to achieve for everyone. You don't want to be in a position where success relies on hard work, great strategy is about achieving an embarrassing amount of success with ordinary everyday efforts that were always going to work out well.

I actually quite like the article because it doesn't seem to be promoting that sort of "goals should be hard" thinking for OKRs.

back then a woman in USSR army, a low level commander, when I asked about how she manages to maintain her authority in those conditions explained to me that you do have to run your soldiers hard, yet giving impossible to complete order is the fastest and surest way to lose respect of your soldiers and as result to lose real authority over them, and to walk that fine line the key thing is to truely know your stuff (they were some very technical radar service department).

I do live by her words - the fist thing I determine about my superiors is whether they know the stuff, and thus how much respect, if any, I should give to them and to their orders :)

Some of these are cultural such as it being safe to give feedback and a propensity to act on what is learnt.

The ability to capture and update the persistent model I mentioned in the post requires the leadership to be aligned on the direction.