Documentation is good, but not great in this area. The things to remember:
- Objects go into divisions for reporting and segmentation.
- Recordings will segment when a division is crossed
- Divisions don't control access
- Access is controlled by roles are assigned to agents by division
So, look at it this way. An apartment building has a mailbox for each apartment and each tenant has a key tow their own mailbox. That is like a role assigned to a user for their one division. Now maybe it is a business and a company might have several boxes, so they either have a key for each box or maybe they have a master key that opens several boxes. This is done by defining the role for several divisions to the user. Now, the mailman has to put mail in all the boxes, so he has a key that opens the entire front of the mailbox. That is equivalent of assigning All Divisions for a role to a user.
What you have to realize that that role will give the user the permissions of that role within the division you assign to them. You can't do this in mass, only individually.