With workfront if a OBJECT is shared with a parent group then it is shared with all users in the subgroups.
My idea is to continue down that line and add the ability to report or communicate with all users in the hierarchy. For instance if you want to send a message to all people in Groups 1, 2, and 3 and those groups are subgroups of Group A you would tag Group A only and ALL would be included. Or you want to do a user report of everyone in Group A and all subgroups you would just do Groups = Group A.
This would greatly simplify the number of groups or teams a person is a part of, yet still allow for grouping of people as appropriate.