This is a follow-up bug to bug 14435 which reactivates an old feature that allows you to store the results of a run report in saved_reports.
Now that this will work again, there should also be an option to clean up the data stored - either from the script, the GUI or ideally from both.
One should have the option to specify the number of results to keep (for example keep two on a report scheduled to run daily, as well as the option to delete saved results - perhaps with a "select all" when viewing saved results for a particular report.
I do get requests from libraries to "clean this up". It does interfere with usability.