In south Florida you may need to replace them twice a year and some times more than that. The sun just tears them up. And most frustrating is no one checks their blades until its raining and you turn them on and find they don’t work very well. At Poirier’s service center we always check the blades at each oil change to be sure you are ready for the rain. In the worst case the metal part of the blade can scratch the windshield.