A couple use cases for this I’ve encountered: - As an application developer, wanting to provide type stubs for a small subset of Luigi’s (the popular data pipeline library) public API. In particular I wanted to fully type the https://github.com/spotify/luigi/blob/master/luigi/parameter.py module since these parameters are descriptor-like in behavior and thus without any stubs make a mess of using any Task attribute. For this use case a module level overlay would work fine. But I did also think about typing single functions within classes that would particularly benefit from overloads and such, for that to work more granular overlay levels would have to be supported or else I would be forced to type the entire class even if I’m fine with basic type inference for the rest of the methods. - Generating partial stubs to replace manual overload boilerplate or things the type system won’t let you do, similar to discussions in https://github.com/python/typing/issues/1371. I think supporting more granular overlays for this would be ideal.