There is a difference between defining methods in `included` and in `ClassMethods` module. First one defines dynamically new methods each time it is included. Second one includes the `ClassMethods` module and shares its methods between classes. First one can also break chain of super calls and probably bring other problems. `InstanceMethods` module is not necessary, the method `host_status_id` can be directly in `HostManagedExtensions` module as in any other module without `ActiveSupport::Concern`.