Look, this stuff is not easy to measure, at all. It's even harder when the two largest platforms (i.e Goog and FB) won't co-operate (for potentially legitimate

Look, this stuff is not easy to measure, at all. It's even harder when the two largest platforms (i.e Goog and FB) won't co-operate (for potentially legitimate privacy reasons). On the other hand, I can assure you that for most niche brands/services (i.e. the ones that spend money on digital advertising), spending $1m dollars on CPM ads on everyone in your audience, versus spending $1mn dollars on optimised advertising will have wildly different impacts on your bottom line. Source: did a lot of ads measurement analysis over the past few years.