Preventive maintenance is far cheaper than emergency repair. A quarterly schedule works well for most offices.
Every month: install operating system and security updates, verify backups and clear temporary files.
Every quarter: physically clean dust from fans and vents, check drive health, review startup programs and confirm antivirus status.
Every year: review hardware age, plan replacements or upgrades, and test your data restore process end to end.
An AMC bundles this schedule with technician visits so nothing gets forgotten.