As an office manager for a real estate office, and the computer guy, and the receptionist, I take all calls, see all the input, the leads for potential buyers and create nearly all marketing.  My agents don't advertise in print as much as I'd like, but we are well represented on the MLS and on the internet.  Nonetheless, there are people who don't have internet, and/or don't want to talk to an agent and/or will simply drive around.  Based especially on calls to our Home Info Hotline, I can source the calls...see where the caller got the ID code.  Most come from a local homes magazine, but a consistent 10 to 15 percent come from the yard sign.  You want every possible lead you can get to be able to contact your agent.  Best wishes.