When you schedule a patch the following occurs:
Note: If you schedule multiple patches for installation on the same machine, all the patches are installed at the same time. After all the patches have been installed the machine reboots once. This technique saves time and reboots.
Note: Service packs are always installed separately. If you are installing a service pack with other patches you will see a reboot after the service pack install and then another single reboot after all the other patches are installed.