You are correct.  Per your policy, the object will be "expired" 5 minutes after it is created, but the actual job to delete expired objects only runs once a day.
 I was doing a test using a CIFS share on an Atmos VE at version 2.0.  There was a policy set for the sub-tenant which set retention at 2 minutes and deletion at 3 minutes.  A file was coped to the Atmos CIFS share and as expected it could not be deleted until the 2 minute retention had expired.Another file was then copied to the CIFS share and left there with the expectation that it would be automatically deleted after 3 minutes. After checking the file 5 min later it had not been deleted. After checking the next day it had not been deleted.  I assume this is because there is some periodic task which when run will delete and files that have exceeded their deletion date ?Is this a correct ? If it is correct how often are files which have passed their delete date deleted ?  Thanks.
How does Deletion Policy work ?