Administrators with permission and access to manage Mailbox Recovery functionality
Archive Task Sync Frequency
Task frequency is currently an automated process and it is not possible to set a custom sync schedule, although you can set 'exclusion' windows.
Each archive task will run 6 times per day so all ll mailboxes included in a task will be synchronized once every 4 hours. The timing of the sync for each mailbox is is distributed and balanced across that 4 hour period.