Here's an overview of Leslie Wood's thinking:
Advertising campaigns typically deliver 90% of their impressions to segments that have very low responsiveness. Refocussing ad spend on people with whom the creative resonates most powerfully can deliver double the ROAS.
Although brand owners aim for their advertising to reflect the brand strategy, once the creative has been finalised, it often turns out to have a bigger impact on people outside the intended core target.
Frequent brand buyers, and heavy category buyers who buy the brand occasionally, are often the most responsive groups. Likewise, non-category buyers can often provide the biggest sales uplifts.
Long-term sales are driven more by incremental sales from existing buyers than from prior non-buyers, but some creative does a better job of motivating consumers who are not normally highly responsive. To maximise ROI, marketers need to know the sales uplifts by consumer segment for a given campaign and target whichever segment is responding best.
The database for these recommendations comes from CPG frequent shopper data. This might or might not generalise to other types of businesses.