Not every network is of the size and complexity that requires delegation of permissions on GPOs. However, many networks are this complicated, so if you’re considering handing off some of the responsibility for GPOs, keep the following issues in mind:
If permission is set to inherit to all child containers, authority delegated at the domain level will affect all objects in the domain.
Permissions granted at the OU level can affect just that OU or that OU plus its child OUs.
Control delegated at the site level is likely to span domains and can influence objects in domains other than the domain where the GPO is located.
Always assign control at the highest OU level possible.
Just about every chore connected with Group Policy ...