What is it with us? I always wait too long. My DH noticed the trouble I was having (exactly what you said) and asked me why I don't change the blade. So I did. Wow, forgot how nice a new blade works. DH asked, "Why did you wait so long to change the blade? You bought a new one months ago." Told him "I'm saving it." What for I don't know. We both got a good laugh out of it. But seriously, I think it because they get dull so fast and they aren't cheap.