Refresh interval for LDAP based mailbox collections

I have a migration setup with QMM 8.14.  Sync and switch collections have been configured to be defined by a value stored in an AD extension attribute.  When this attribute is changed, mailboxes move from a sync group to a switch group as expected.  There is a need to switch mailboxes "on demand" and when we do this, it takes somewhere between 10 and 20 minutes to be removed from the sync collection and added to the switch collection.  Reviewing the logs, I can see that the collections refresh their members via LDAP query every 15 minutes.  Is there a way to adjust the time between refreshes?  Alternatively, is there a preferred method to accomplish automated mailbox switching via script?