I agree that it is easy for a metric to loose it's original meaning. I've had luck with OKRs; Having a non quantitative goal, and possibly changing quantitative based targets aimed at making the goal happen.
It's great to see all the good competition in this area. The more use, discussion, and cross pollination among them the better. Here's another one (Akkeris) I've used, open sourced by an excellent former employer and devops team: https://beta.akkeris.io/
My brother in law just finished a residency and we asked him the same question. Apparently more mistakes are made in hand offs between doctors than from tired doctors.