Reach vs. Frequency: Fifty Years of Disagreement, and What It Means for Budget Allocation

The question that will not settle

Every media budget implicitly answers the same question: given a fixed number of dollars, is it better to reach more people once, or the same people more times? The answer has been argued, revised, and re-argued for over fifty years, and the debate is not academic trivia. It directly determines whether a marketing budget should be spent chasing new buyers or repeating exposure on buyers already reached.

1972: the three-exposure model

Herbert Krugman's "Why Three Exposures May Be Enough," published in the Journal of Advertising Research in 1972, proposed a cognitive model: the first exposure to an ad prompts "what is it?", the second prompts "what of it?", and the third produces a decision. Further exposures beyond the third, in Krugman's framing, mostly just repeat the effect of the third and add diminishing value.

This became the founding paper of effective-frequency theory and shaped decades of media-buying convention around minimum frequency thresholds. It was also, from the start, a theoretical model rather than a large-sample empirical study, and later research has both built on it and challenged its specific numbers.

The reach-first counter-evidence

The Ehrenberg-Bass Institute for Marketing Science accumulated over forty years of purchase-response data and found the response curve to advertising exposure is convex, not S-shaped: the largest incremental purchase stimulus comes from the zero-to-one exposure, meaning each additional exposure to an already-reached buyer tends to return less than reaching a new buyer for the first time. This finding underwrites the Institute's "maximize reach" doctrine, documented at length in Byron Sharp's How Brands Grow, and it has become the dominant orthodoxy in evidence-based media planning over the past decade.

Erwin Ephron's recency-planning framework operationalized a version of this into an applied media-buying discipline: reach a consumer close to their in-market purchase decision, rather than repeat exposure on someone already reached, because reach and continuity, not frequency-building, tend to be the more efficient buy for a reachable audience.

A genuine, live counter-argument

The reach-first doctrine is not unanimous. 2024 practitioner coverage, reported by Mi3, cited newer attention-technology data suggesting that in fragmented modern media environments, optimal frequency may actually run higher than the old three-exposure rule, in the range of seven to nine exposures, before returns meaningfully diminish. The argument is that today's media environment is noisier and more fragmented than the one Krugman or the early Ehrenberg-Bass data was measured in, which could plausibly raise the number of exposures needed to register.

This is a genuinely contested point in the field, not a settled question with a fringe dissenter. It deserves to be presented as a live disagreement between credible positions, not resolved in either direction by citation count alone.

Why the disagreement itself is the useful finding

Fifty years of research producing a live, unresolved disagreement is not a failure of the field, it is evidence that the correct answer is contingent rather than universal. The strength of the reach-first evidence, the theoretical logic of the three-exposure model, and the emerging attention-fragmentation argument together suggest that where the optimal reach-to-frequency balance actually sits depends on the category, the media environment, and the specific audience being reached, not on a single number that applies everywhere.

Treating any one figure, three exposures, or seven to nine, as a universal rule to apply to every business and every channel misreads the evidence. What the literature actually supports is a method: measure the marginal return of the next exposure for a specific audience on a specific surface, rather than assume the answer from a rule built on a different media environment decades ago.

What this means for budget allocation in practice

A defensible allocation decision asks where the next dollar's marginal attention-return is currently highest: on a surface where the business has not yet reached a meaningful share of its potential buyers, or on repeating exposure to an audience that has already been reached and is close to a purchase decision. Both can be correct answers, for different businesses, at different points in their growth, on different surfaces.

This is precisely why reach-versus-frequency is a question to answer empirically, per domain, rather than to resolve once with a fixed frequency cap applied uniformly across every campaign a business runs.