Yes, the round-robin setting goes to every available destination in turn. I think that blacklisting items you don't want ending up down a particular path is a great idea.
I don't like the idea of blacklisting an item void as that can come back to bite you later on. For what I want to do, I'm just going to have to use a buffer for each item I want to distribute round-robin-style and keep that ducting separate. This way I can get what I want do how I want it done and not worry about overflow backfilling into places where it shouldn't.