The answer to 'surge protector replacement schedule' is that surge protectors should typically be replaced every 3-5 years, or sooner if they have been subjected to a major power surge. Surge protectors wear out over time and lose their ability to effectively protect your electronics from voltage spikes and surges. Replacing them on a regular schedule helps ensure your valuable devices stay protected.
Many surge protectors also have indicator lights that can signal when the protection has been compromised. If the light goes out or changes color, it's a sign the surge protector needs to be replaced. It's also a good idea to replace any surge protector that has been exposed to a major power surge, as the internal components may be damaged even if the lights are still on.