Using flyers as a Marketing Tool

[Travis Newton]

Quick question I've read a few times here on BP that its good to flyer a neighborhood as part of a marketing campaign. My question is why would I flyer an entire neighborhood, that sounds like a waste of flyers as not everyone in the neighborhood is looking to sell their home or is a motivated flyer. Also is flyer defined as the 4x6 flyer that is commonly used by businesses?

Thanks!!