MS Dynamics CRM 2013 how is the rights inheritance hierarchy done?

Question

CRM

Hello. Now CRM is setting up an organizational structure. We have Dynamics specialists. I want to ask you. How is tree inheritance implemented based on Divisions and Workgroups?
What we know and understand:
1 - when a Division is created, a Working Group of the same name is created.
2 - The Working Group cannot be owned by another Working Group, but only by a division.
The management proposes to create 5 divisions (main). Next, create Working Groups and set these units for them.
The fact is that the organizational structure is not 2-level. The tree has at least 5 levels of nesting. If you listen to the manual, then we will get a 2-level structure at the output, in which the first level will be one of the 5 main Divisions, and the second will be all its child links (Working Groups).
Maybe I missed something, and then on the basis of this 2-level structure it will be possible to make hierarchical Security Roles, but I doubt something. I think it is necessary to create hierarchical Subdivisions (and they, in turn, will create hierarchical working groups) and in the future, using the created WGs, set Security Roles.
Please tell me how to do it right.
UPD1: neither I nor the management have any idea about the importance and significance of the Divisions and Working Groups yet