Comment by slwvx

I was not aware of (or had forgotten) the term "Wright's law" [1], but that indeed is what I was thinking of. It looks like some may use the term "learning curve" to refer to the same idea (efficiency gains that follow investment); the Wikipedia page on "Learning curve" [2] includes references to Wright.

[1] https://en.wikipedia.org/wiki/Experience_curve_effect

[2] https://en.wikipedia.org/wiki/Learning_curve