Yeah, it pretty much doesn't work well. The unit economics is something like "pay 50 cents a click and hope your funnel can monetize that effectively". More if

Yeah, it pretty much doesn't work well. The unit economics is something like "pay 50 cents a click and hope your funnel can monetize that effectively". More if you have more specific/desirable targeting, less if it's broader, but anything you save on the targeting end you lose in funnel effectiveness. If you've got solid data all the way through to conversions and lifetime value, that can either justify dialing ad spend up or down, and it's usually going to be down.