MDU inventory--network site vs parent account

For assigning equipment installed at an MDU that is not tied to any given account (e.g. a switch in a utility room) is the best practice to create a network site for the building or a parent account to all of the customer accounts in the building?

We create a network site for any building that has more than 1 customer in it (or will have more than one customer). All infrastructure inventory is then tracked in the network site, not at the customer level.