Whoops, yes that is indeed a union not an intersection. Thanks for the correction. I'm still getting used to the terminology.

The explicitness I was referencing is around the declaration merging. Its automatic so unless there's a conflict between two interfaces with the same name but with different properties, a dev wouldn't know that it was being done.

I agree with using what makes sense for the scenario. I prefer type aliases for functions and interfaces for classes and that seems to work out pretty well so far.