When creating Policies in NG Firewall Policy Manager app, the power of the parent/child relationship is often overlooked.
The primary advantage to using this relationship is ease of management. When you create a child Policy, it automatically inherits all of the apps and configurations from the parent Policy.
This allows you to install only the applications that you want to be different from the parent Policy.
Example: in most networks, Spam Blocker, Virus Blocker, Phish Blocker, etc. will be the same for everyone. There is no need to have those installed and running in every Policy. In fact, if you are low on resources, this can actually be detrimental to your NG Firewall's performance.
More information on that can be found HERE.