Only a user who enables schedule archiving is able to see its schedule in Archive settings.
The administrator will not be able to find whether or not the user enables schedule archiving. This is because ArchiveProfile is created for each user and the scheduled Compact -A is saved in its local names.nsf.
The only way the administrator can find if a user enables schedule archiving is using NotesPeek and see Profiles > archive profile > ScheduleArchiveEnabled.
I request Notes to have the ability to show on UI an Administrator if any users enable schedule archiving without using NotesPeek.