ADOM setting "Default Device Selection for Install"

When you create or edit an ADOM this setting give you a choice of Select all or Unselect all. What does this setting do? All the documentation I've been able to find just says to choose one, never says what one does compared to the other.

My ultimate goal is to have Fortimanage organized so clients with a single FG are all in in ADOM, and any client with multiple FGs have there own ADOM, and in both cases I don't want Fortimanage to push out anything based on any group/ADOM, no policies, nothing. Just a way to manage the FGs independently. 

Thanks