When retargeting stops being efficient

It is the best-performing line in most media reports and the least incremental. Both things are true at once, which is why the argument never ends.

Written by the Colleviate Performance desk

Retargeting shows people an ad for something they already looked at. Of course it converts. The question is never whether it converts, it is how many of those conversions needed the ad at all.

Why the reported number flatters

Attribution credits the last touch before purchase, and retargeting is engineered to be the last touch. Somebody who was coming back anyway sees your ad on the way, clicks it, and the channel claims the sale. Reported return is excellent. Incremental return can be close to zero.

The test that settles it

Hold out a random share of your retargeting audience for four weeks. Compare conversion rates between the suppressed group and the targeted group. The difference is the incremental effect. It is the cheapest high-value test in paid media and almost nobody runs it, because the answer is often uncomfortable.

The frequency problem

Past a certain point retargeting stops persuading and starts irritating. There is no universal number, but the signal is easy to read: rising frequency with falling click-through and no lift in conversion rate. Cap it, exclude recent purchasers, and exclude people who have seen the asset more than a handful of times.

Sizing it honestly

Retargeting should be a small, capped share of paid budget: enough to catch genuine abandonment, not enough to re-bill your existing demand. Where the real work sits is upstream, in creating demand that does not yet exist, as argued in brand versus performance, and downstream in owned channels, which cost nothing per message: see email and lifecycle marketing.