GoodhartsLaw

https://freakonometrics.hypotheses.org/63816

To use Farrell’s (2012) image, let us imagine a driver driving on a very hilly road at a constant speed. With ups and downs, this means that the driver perfectly doses his or her acceleration and braking to control the speed. However, seen from a distance, one would be tempted to say that the level of acceleration has no impact on speed, and that if we were to regress the speed on the acceleration of the car, the correlation between the two would be zero, in other words, here, accelerating and decelerating has no influence on speed…

I'm not sure how to apply this observation to software but it seems pretty deep.