An hour later you return to the problem, solve it, and move onto other tasks. Suddenly, another problem flares up. My recommendations vary wildly depending on the circumstances, but some common themes have emerged, and they might serve as the keys to your new firehouse. Postmaster mail arrives and needs to be handled.
Disks get full and space needs to be juggled.
Users delete files and need help retrieving them. New systems arrive and each one needs to be installed, configured, tested, debugged, and delivered to the users. Unfortunately, blaming users for being users is counterproductive and can lead to sysadmin burnout. Rather, look to the methods being used, because solving a problem more than once is a waste of time. They all take time to resolve.