We use service desk for different types of requests.

For certain type of requests, we have a need for everyone under a user group to be able to see the requests.

for example.

We would create a user group called NPI Viewers and a service category or request type named NPI.

All NPI requests would be visible to everyone in that user group.

At the moment the only work around we have is to manually share every ticket with requesters. 

Editing requesters to view all their departments or site requests doesn't work as we want to maintain requests under other service categories private and this wouldn't allow them to see requesters submitted by users under other departments or sites.