Before SCCM, we used to use a software deployment solution which would prevent users from logging while a package is being installed. It would also display on screen what is being installed and once finished, the PC would restart if required or just present the logon screen.
Can something similar be done in SCCM? The "Only when no user is logged on" option is not much use to situations where the users log on straight after they power on their machines or for software updates that need to be installed urgently while no user is logged on (like software that requires that internet browsers or office applications are closed).