I think if your library app has a reload task assigned then you should set this to update daily. All other apps should then be updated if you have applied the custom properties to those apps.
This is because you have to specify the reload task in GMS Setup;
I believe it monitors this task and 'pushes' out the new library after the task completes.
@Erik, GMS is a REST api so you can set up a schedule to kick off a reload and update through a job in scheduler or some other scheduling solution of your choice. You are not obligated to use the testpage. API docs: http://eapowertools.github.io/GovernedMetricsService/gmsapi/