“The single biggest problem in communication is the illusion that it has taken place.”
Did GBS actually say that, or is it mis-attributed? In any case, the point holds true: communication often fails. It succeeds only when information is successfully transferred and understood.
It is often assumed that if people are exposed to a message once, then communication has been achieved. In fact, someone may need to hear something many times before the information is absorbed and leads to a response.
Some say seven times: the first two to build awareness, then the next two to develop interest. The following two may lead to some kind of commitment or decision to respond, but only when the message is heard the seventh time might there be tangible action.
Of course there are exceptions, but it’s a good general rule: that’s why advertisers bombard us with the same message over and over again. They want tangible action. They know that repetition is more likely to induce a response.