Container map is read from the home container first if that fails for any reason, the container map in "shared container" is read instead, so you only need the shared copy. Reason for not using Admin is that shared is open for all developers, while Admin should only be open by the once managing the framework. And the reasoning for having a container map in every container is that you might not have access to shared.
You can change the behaviour in 4.GenericContainerLoader.qvs where it refers to call LoadContainerMap. Hope this helps, regards Magnus