When setting Reports to Keep value it is noticed that it does not get cleaned up for 24hrs. After the first day reports published to NewsStand are subject to a cleanup period of 30 minutes.
Reports to keep is not enforced prior to reaching the Days to keep of minimum value "1". This causes reports to accumulate past the set Reports to keep value in the first day after the publish task has been set/run. This is working per design as setting Days to Keep equal to "0" is currently not allowed.