Why is it that my SUS clients can detect and install Service Packs all by themselves but the detection process needs to run again to pick up any updates?

Contributed By: Cliff Hobbs [MVP SMS]
Reproduced from the Microsoft Software Update Services: Frequently Asked Questions web page:

http://www.microsoft.com/windowsserversystem/sus/susfaq.mspx#top

"Service packs (as well as certain other updates) are exclusive in nature, meaning that they should be installed separately from any other update. When the Automatic Updates client detects updates and one of them is exclusive, only the exclusive update will be offered for install on the client machines. This ensures that after install and reboot, the next detection cycle by the Automatic Updates client will offer and install only updates that are applicable to the new service pack."