By default Apple Software Update Server’s (READ: ASUS) sync daily with Apple at 3am.
But this can be changed, & the below script can be ran to change the interval. You can change either the time of day the sync runs or change it to once a week.
As the LaunchDaemon is located within the Server.app, you’ll need to run this after every update to Server.app.
As mentioned elsewhere, we cascade out ASUS’s. We use the above script to stagger these updates incase of a bad update being released.
Our master is set to run it’s sync every Sunday at 8pm, with the replica’s every Saturday at 8pm. If a bad updated is released, we merely stop the ASUS service on the master before the replica’s sync on the following Saturday.