The policy check tool allows you to check all policy packages within an ADOM to ensure consistency and eliminate conflicts that may prevent your devices from passing traffic. This allows you to optimize your policy sets and potentially reduce the size of your databases. The check will verify:
1. Object duplication: two objects that have identical definitions
2. Object shadowing: a higher priority object completely encompasses another object of the same type
3. Object overlap: one object partially overlaps another object of the same type
4. Object orphaning: an object has been defined but has not been used anywhere.
Reference: https://docs.fortinet.com/uploaded/files/2905/FortiManager-5.4.0-Administration-Guide.pdf