Storage usage limits for mobile app file cache/downloads
An optional limit to the amount of storage used by the mobile apps to download recently used files. Otherwise a limit to the number of files cached in this manner based on how recently they were used or a limit on how long it keeps them on the mobile device.
This would allow users to save space on the mobile device. Keeping only documents they expect to use easily accessible.
Along with a keep on device setting for important files to provide users control over this functionality.