Wiper blades, in general, should be replaced every 6-12 months, as warranted. They are important safety items as they allow you to see clearly while driving in inclement weather. They should be checked each time you clean your winshield, or at every fuel stop, for wear or cracking. Try and avoid touching the blade directly, as the oils present in your fingers will accelerate the rate at which the rubber compound breaks down. A blade that has dried out and started cracking will smear the water across your winshield, hampering your vision.