Guidance for when to create a new SD project vs combining under one

[Jason Walker]

I have a client with many different departments that all want to use Jira Service Desk for their own purposes.  In some cases, it seems to make sense for a department to have an manage a separate project and for others to converge on one project.  I have been looking for any guidance out there that might help me steer their decisions so that we don't end up with a mess down the road.   

Does anyone know of a resource that discusses the arguments for combining work into one project versus breaking it out?  I am specifically thinking about the implications for:

• Customer experience
• Agent collaboration
• Knowledge management
• Reporting

Any suggestions greatly appreciated.  Thanks.