https://groups.google.com/forum/#!topic/foreman-users/D9sCDwUpSKo

The above conversation is around multiple host group assignments (something I think is still useful, just add a precedence to figure out setting clashes).

In my case I was creating a hierarchy of host groups when the majority of the host group settings were identical (at the role level). It was suggested that I set some of the settings I was in the host group via the Locations settings. However while you can set what smart proxy and compute resources are applicable to a certain location you can't set them as the default. Therefore you still much explicitly set that either via the host creation page or within a host group.