Group policy can be simplified by just providing policy based administration for users, groups, workstations and servers. This is not a concern because with multiple domains users are not confined to a particular domain, they have all access with their personalized settings as per the domain they belong to and can be made available on all computers. It enhances the security.
You can start with one single policy for all users and seggregate them on domain basis. This will allow more of domain-specific access, which will also overcome flaws, if any at organization Level.
