Hi Simon,
Great question!
As customers first start to deploy the "Tickets" object, I generally recommend they think solely in terms of "IT Help Desk/Service Desk" tickets, thus we simply allocate the "End User - Service Desk" ITRT across the entire population of tickets.
That being said, I have had a few clients who have wanted to expand out the tickets object above and beyond that view, with some of the items you listed above. A few options:
1. Allocate additional IT Towers and Sub Towers
End User - Field Support
Application - App Support & Ops (Change Requests)
2. You can also leverage the 'Resource Tower Metadata 1' and 'Resource Tower Metadata 2' fields in IT Resource Tower Masterdata to include additional granularity of a single Tower/Sub Tower. For example:
IT Tower IT Sub Tower Metadata 1
End User Service Desk Incident
End User Service Desk Change Request
End User Service Desk Problem
End User Service Desk Change Task
You could then add this metadata field to your key from ITRT to Tickets, thus giving you additional allocation granularity.
Hope that helps!