Don’t you just hate the feeling when you think you have some module in your project that may make sense to be an open-source library, but as you document its features, you start to second-guess everything about the module’s worth? I mean I probably shouldn’t guess anything, but I can’t seem to help it.

Do you have any examples of libraries?

Application development and library development are two completely different beasts.

App dev is less concerned on aspects like reusability or use cases for a (self-written) module since it usually only needs it for a very particular use, but the moment you start to reason about it as if you were a third party dev using the module for unrelated things, these issues are bound to creep up.