We have recently moved over to HubSpot from another helpdesk system. Our previous system had a very clear and easy way to see and navigate all teams and agents tickets. It was a explorer view that showed the counts of open or unassigned tickets at the team or agent level, as show below.
By selecting the team or agent on the left hand panel then showed all tickets in the list on the right hand side and then further across the preview of the ticket. This was done without having to click to enter into individual tickets.
This is especially useful when a helpdesk manager is trying to load balance tickets across the team and can drag and drop tickets to the relevant agent. Our entrire team really miss this useful way of navigating tickets.