#2 splits the configuration into 'dev' & 'prod' duplicates, describes it as 'with separate state files', and from there they're all different ways of splitting the project for some reason.
If the state isn't local, then if you want that split in order to apply them separately, there would be no reason to physically separate & duplicate them into different directories.
If the state isn't local, then if you want that split in order to apply them separately, there would be no reason to physically separate & duplicate them into different directories.