Permissions - Highest value vs lowest value priority?

[Joe Link]

Permission is set to allow Registered usergroup to perform an action every 300 seconds and Upgraded usergroup to perform the action every 100 seconds. Being a privilege, I want the lowest value to take priority rather than the highest.

Where/how is this determined?

 

[Joe Link]

Just to clarify, here's an example of an add-on which is doing it correctly.



Versus what I'm trying to do.

 

[Paul B]

Is this something you are developing yourself or is it from a third party add-on?