That's one of the conclusions of "Advertising Reach & Frequency: Maximizing Advertising Results Through Effective Frequency," published this month by the Association of National Advertisers. The book dispels the "three-plus" frequency rule that has been the foundation for many media plans for nearly two decades.
The rule held that three was the optimum number of exposures an ad had to have with a target to be effective. Fewer exposures risked little or no impact; more meant a diminishing return.
The rule was part of an 1979 ANA volume on the same topic. But many marketers, particularly less-sophisticated ones or those without the research resources to conduct their own brand frequency studies, seized on the principle as gospel.
"For many people, three-plus became a rule of thumb. That's not what I intended," said Michael Naples, president of the Advertising Research Foundation. He wrote the first edition while he was director of marketing research at Lever Bros. "What I said was that each brand should .*.*. figure out what its own curve was."
Mr. Naples said he had hoped marketers would further refine the theory with new means of market research that were becoming available in 1979, including a proliferation of supermarket scanner data and so-called single-source research laboratories at Nielsen Marketing Research, Information Resources Inc. and others.
Instead, he said, virtually no new research was done on the topic from 1980 to 1990, noting single-source labs have been abandoned due to high costs.
It was for these reasons that the ANA asked Mr. Naples to revise his earlier work. But due to his ARF responsibilities, he turned the project over to British media researcher Colin McDonald, whom he worked closely with on developing the new book.
Mr. Naples said three-plus is still a valid generalization, but doesn't address a number of practical variables.
The problem, he said, is the rule is based on an idealized situation of a new brand, breaking an ad within a specific cycle.
In reality, he noted many big brands are constantly advertising and that for many of them, one exposure to an ad might be effective.
It is those nuances and variables that Mr. McDonald's new book builds on. And although his new conclusion is that two exposures to an ad within a purchase cycle is a new model for optimum frequency, he hopes that today's ad practitioners don't interpret the number as gospel either.
"I think that three-plus has been thrown out of the window as a general rule. It was based on a somewhat insecure foundation of learning theory and it treated advertising as a form of learning," Mr. McDonald said.
Instead, he said there are a wide variety of variables, including how old the brand is and how well known it already is among its targets.
"Most advertising is reminding people about products they already know about," Mr. McDonald said. "...For those brands, two is probably an effective frequency."
Another key component of Mr. McDonald's new work is that the timing of ad exposure is just as critical as frequency, and that ads that hit targets during a purchase cycle are more effective and require less frequency than ads that don't.