Use cases for separate hives within Aerohive?

I'm still trying to learn how to manage an Aerohive environment that I am inheriting. I've been going over whatever documentation that I could find. But I haven't yet found anything in depth about hives apart from the general definition:

A hive is a set of Aerohive devices that exchange information with each other to form a collaborative whole. Through coordinated actions based on shared information, hive members can provide the following services:

Consistent QoS (quality of service) policy enforcement across all hive members

Coordinated and predictive wireless access control that provides seamless Layer 2 and Layer 3 roaming to clients moving from one hive member to another

Dynamic best-path routing for optimized data forwarding and network path redundancy

Automatic radio frequency and power selection for wireless mesh and access radios

Tunneling of client traffic from one hive member to another, such as the tunneling of guest traffic from a device in the internal network to another device in the corporate DMZ

Hive members use WPA-PSK (Wi-Fi Protected Access with a preshared key) to exchange keys and secure wireless hive communications. To authenticate and encrypt wireless hive communications, hive members use open authentication and CCMP (AES) encryption. CCMP is a rough acronym for "Counter Mode with Cipher Block Chaining Message Authentication Code Protocol "that makes use of AES (Advanced Encryption Standard).

The members of a hive can be in the same subnet or different subnets, allowing clients to roam across subnet boundaries.

What scenario(s) would one consider creating multiple hives versus a single one?

Is it good to have one hive per physical location? APs at a branch office would not need to worry about clients roaming to APs at another office 100s of miles away - so all of the peer-information sharing wouldn't be necessary over the WAN right?

I also don't know what configuration objects can be shared between hives - or if they need to be separately defined. How much additional management is required if managing multiple hives? Is it extra work to have the same Network Policy and SSID available on all hives for something like an Employee network?

Thanks in advance