So about 90% (or more) of our users don’t have the same content appearing on multiple site folders at the same time. It would be a great feature if when inserting items into a slot, there was some javascript (or some extension that is enabled by default) that could determine if the site and folder links need to be checked (and do so automatically).
The end user should not care what site or folder the content is coming from…after all this is a “content management” system and sharing content should be made as easy as possible.