How to avoid specifying User Name in Manage Segment Value Security spreadsheet?

Summary:

Segment Value Security spreadsheet includes two worksheet tabs - Rules and Rule Assignment. Among many columns in the Rules worksheet tab, it includes the columns Policy Name and Role Name, which helps to associate a security rule Policy with a specific Role. In the Rule Assignment spreadsheet, it includes columns User Name, Policy Name and Role Name. Now why do we have to populate User Name in the Rule Assignment worksheet tab? How can I ensure that all users who have the Role that I have associated with the security role Policy is assigned with the related security rule please?