This policy setting allows you to set an upper limit on the sleep interval used by the cache. The sleep is automatically ...

This policy setting  allows you to set an upper limit on the sleep interval used by the cache.  The sleep is automatically interrupted when any application made changes in the cache or if there is an action scheduled to be performed.
    
If you enable this policy setting, you may specify how long (in minutes) the synchronization should wait before resuming when there is no pending work to do.

If you disable or do not configure this policy setting, then a default value of 20 minutes will be used.