This is something you probably want to care about when you're producing text in some kind of professional capacity, for e.g. a newspaper, book, documentation, or something like that. You will need a manual of style to maintain consistency of the work across multiple authors. Using a single space is a universal rule in every typesetting/style manual I've ever seen, so it's the correct choice in that case.

If you're just out typing stuff in informal correspondence, as a hobby, or otherwise, I don't really think you need to care.