I'd be happy with the idea of the admins graveyarding abandoned entries. It ought to be possible to automate the process, except that I haven't yet found time to get my two GWL tools working since flickr changes some years ago.
That Belsize Village GWL? How nice to be remembered after all these years!
Whatever the concurrent limit, we can also limit the number of postings to say 3 per member day - or you could in IP so I'm assuming it's possible in flickr. That way it stops someone dumping ten on the group and then forgetting about them.