You do not need a reporting habit that takes an hour. Five numbers, once a week, will tell you almost everything.
Ticket volume broken down by category tells you what your customers keep needing. If one category is a third of everything, that is a knowledge base article or a product fix, not a staffing problem.
The metric customers actually feel. Watch the trend rather than the number: a first response time that is creeping up week on week is the earliest warning that the team is over capacity.
The dashboard shows resolved within SLA against resolved outside it, and you can click either figure to see the individual tickets. Do that - the pattern in the breaches is more useful than the percentage.
A closed ticket that comes back was not solved the first time. A rising reopen rate usually means the team is closing tickets to hit a target rather than because the customer is finished.
Who is carrying what. The timesheet view shows time spent per ticket and per agent, which is the honest input to a staffing conversation.
The dashboard covers volume and SLA compliance at a glance. For anything you want to keep, go to Reports > Custom Reports > Ticket Performance, set the date range, and include the Resolved Status field to see performance against SLA per ticket. All of this is on the free plan.
Compare against last week, not against a target you invented. Two consecutive weeks moving the wrong way is a signal; one week is noise.