If the coding doesn't work for you, and you'd rather not set permissions on each file, then there is a third option. We use folders with permissions set on them.
e.g.
Create a folder called "Managers", break permissions, and set rights to only the managers.
Create another folder called "Employee 1", break permissions, and set Contribute rights to the Employee and the Employe's manager.
Place the files in the appropriate folders and it will inherit rights from the folder.
This way, managers can see the manager files, and all files of their employees. Users can only see their own files.
Similar logic can be done for Headquarters, Region 1, Region 2, etc ... and creating different Groups for each region and then assigning the group to the folder's permissions.
Note, there's always concern in using this design on maintaining all the permissions and on performance, but we've been doing similar things for 750+ user populations and thousand of docs and it's been working fine for us so far.
Henry