Our approvals are based on our org chart. It works well.
1. Set up your approval routes to mirror your org chart. Mine have a two character code to indicate department followed by a hyphen and a three code character to indicate division.
2. In Default Locations & Printers, put that code into each record of people who will be entering requisitions.
3. In P4310 processing options, set the Route Code PO equal to 4.
That's all.
In our case, we also have administrative support staff who enter requisitions for more than one division. I set up special menus for them that have P4310 versions with the approval route hard coded in the Route Code processing option, so all they have to do is select a certain menu item to direct a requisition down that approval route.