If your goal is to get all systems up to current release just create a policy for all systems to run at ANY or perhaps your 30 minute interval that use the 'Update Command Line Applications' option on the general tab of a policy. It will update anything that is checking in properly and ignore those that don't need it.
We've actually had a policy in our system forever called Update_JAMF_Binary that I just flush each time a new version comes out and clients just update themselves...if I'm confident the binary won't break anything. =)
Craig
