This is so subjective. What is acceptable in a windshield wiper for you, may not be any good for me. I may have replaced wiper blades long before someone else, because I wasn't happy with them.
That said, I replace wiper blades about yearly, give or take when it matches up with a service on the car. I don't wait until the performance starts degrading. Who wants to get caught in that rainstorm, and not have good wiper blades.
That said, I replace wiper blades about yearly, give or take when it matches up with a service on the car. I don't wait until the performance starts degrading. Who wants to get caught in that rainstorm, and not have good wiper blades.