This code is “clever” because it exploits knowledge about the language, in this case the peculiarities of fall-through. Clever code can also exploit knowledge about the operating environment or special topics like bit twiddling. Conventional wisdom says this clever code is “bad”.
There’s a second kind of “clever code”: code which exploits knowledge about the problem.
clever is specifc, niche knowledge about the material or the problem which cannot be extended to another material or problem (respectively) -> acknowledging contextual constraints
in the case of exploiting the problem, that often means that the problem is made simpler, and so the code is made simpler -> that’s insightful
but if the problem changes, that insight might disappear: such a code is read-only because relies on tacit knowledge and doesn’t transfer between people
Expert C programmers argue they don’t need memory safety, expert Clojurists argue that static types wouldn’t help them, etc.