Process Scheduler Notifications

There are 2 places where process scheduler notifications can be configured:

PeopleTools > Process Scheduler > Process Scheduler Settings > Process System

Then, for each specific process, it can be configured here

PeopleTools > Process Scheduler > Process Scheduler Processes

We are trying to understand, with Notification Composer configured and turned on, is the configuration using Process Scheduler Settings a Global Setting?

Reason, despite choosing only "On Error" using Process Scheduler Settings, system allows for individual process, options such as "On Success" even though this was turned off at Process Scheduler Settings level

If each process can be configured to receive notifications for run status that was turned off at process scheduler notification, what is the advantage of setting at Process Scheduler level?