What capability do logical networks provide?

Logical Networks allow you to create fewer Network Access Policies than before. (FortiNAC - What's new in FortiNAC 7.2)

Logical networks in FortiNAC decouple a policy from a specific access value, allowing for the application of different access values from a single access policy. This is done based on the point of connection, significantly reducing the number of network access policies needed and simplifying network access policy management​