Indell on "[Plugin: Easy Pie Maintenance Mode] Missing instructions on how it works"

Hi,
This is the 4:th Maintenance plugin I install and it seems easiest so far. But they all have one problem in common: No instruction when/how the Maintenance page kicks in.
What I want is that the Maintenance page shows only during plugin updates, i.e. instead of the core maintenance message. How do I get that? If I check Enabled = Yes, the Maintenance page is on all the time. That is not what I want. Please help me understand.

https://wordpress.org/plugins/easy-pie-maintenance-mode/