There's a word hovering in the background throughout this article, but it never makes it onto the page: judgement. In software development, for example, there

There's a word hovering in the background throughout this article, but it never makes it onto the page: judgement. In software development, for example, there is a lot of explicit knowledge to learn, and then there are the mental models about how one should apply that knowledge - e.g. SOLID - but these models do not tell you exactly what to do (in particular, there are all sorts of ways of using the rules to justify bad decisions.) It takes good judgment, honed by experience, to apply the rules effectively.