A case for door to door evangelism?

Jehovah's witnesses claim that they need to knock on 740 doors for each convert. I am not sure if they have exagerated this to make their evangelism see more effective, but if this is accurate then it is a lot lot better "odds" then I would have guessed. I know what is true from talking to Jaydubs is that many more people are open to door to door evangelism then we may like to think. So should we all put on our shirts and ties and get door knocking?? LOL