on our site, we originally started with only one organization and one location, like most people seem to.
We later added a second organization just to handle some trouble we had with how subscriprion-manager and candlepin reacted to the presence of “special purpose” subcription for things like OpenShift. We were struggling with those subscriptions randomly being handet to standard RHEL servers or their hypervisors, which are the majority of our datacenter, and wanted those special subscriptions to be tucked away so we would not have juggle subscrions around permanently.
Recently, we added a third organization for windows servers only, to ensure the windows people can only see and work with windows related things and the other way around for the linux folks.
Concerning locations, we are now also at a total of 3, with the additional locations resembling logiically distinct parts of our datacenter (you can think of this like “internal datacenter network” and DMZ). Apart from filtering purposes, we also use this distinction for assigning the correct smart-proxies, compute resources, etc.
We have never had a use-case for nesting anything in this area (and probably never will).
Concerning sharing of resources, we use this feature quite a lot. We share everything between both organizations and locations that is possible and does not need to differ. Probably our biggest pain-point in this regard is that resource sharing is somewhat inconsistent in a lot of areas. There are some things that must be shared (like operating systems and their settings), some things that can not be shared (at least between organizations) like anything content related, and finally things that can optionally be shared (like hostgroups) but might break at one point or another because they can contain references to things that are not or cannot be shared.
In our use-case, I could imagine merging the organizations and doing the good old “Windows vs Linux” thing through location filtering. But that would require a working solution for our candlepin/subman problem, since I do not feel like rearranging a lot of subscriptions on a regular basis ever again.
Having locations merged would probably also work, but would require us to blow our already bloated host-group structer up even more, probably resulting in even more redundant data in many of them. This possibly could be solved with a major rethinking of how we use hostgroups, but by now we did not really have time to invest into this department despite the fact it is probably needed, but that’s a different problem
If you want more info on any of these areas, feel free to DM me and I will see what I can provide