(Written from the context of advertising as a professional services provider to business) Understand this one thing and you have taken a major leap in understanding: "Advertising can never stand alone to produce results."
So often I hear law firm marketers and attorneys stating that advertising cannot be measured and is inherently a waste of budget. With deeper questioning I hear that advertising is expected to stand on its own to produce new business -- as if the firm had deployed a person to be face-to-face with potential customers. That's like saying to look at a CD cover is as good as hearing the music. Not true! Advertising only works if it is an integral part of a larger program with other parts.
Last year I started a high volume ad campaign with a business journal local to a business market I am pursuing. In addition to the paid advertising I launched a PR campaign and sponsorship initiative that focused on the same target market as the readers of the local journal. Behind those direct tactics we engaged in targeting specific people in the business network who could exert influence on our behalf.
Only by combining ALL of the elements of the overall initiative can the advertising have a desired result. Advertising CANNOT stand alone.