I also implemented the maxNewsItems solution.
It keeps really old content from sticking around (I was seeing feeds from over a month old) but it favors one of the three feeds I have added in now, only displaying items from that feed and ignoring the rest.
It would be cool to see an update where it pulls one item from every feed added before adding a second item from the same feed.
i.e. Feeds 1, 2 & 3 - pulls one from feed 1, then one from feed 2, then one from feed 3, then another from feed 1, another from feed 2, etc.