Honestly, I doubt these unique pdf's will ever be intentionally saved. Saving the files would be a waste of resources even if they were periodically cleaned up. The bulk are one-time disposable transaction reports or stock mass mailings that will be printed, mailed, and never viewed again. Even if they are later needed, the saved report will most likely be obsolete and require a re-generation anyway.
However, that's not to say that I won't be saving any of them. It's just that THESE won't need to be saved.