If you want to gauge effectiveness do an incrementality test with a test and control group to see your lift. I’ve found retargeting effectiveness to be highly

If you want to gauge effectiveness do an incrementality test with a test and control group to see your lift. I’ve found retargeting effectiveness to be highly dependent on the inventory, ad units and creative, while also requiring a robust attribution model to gauge the effect. Without those tools, it is just throwing money at the wall without being able to see if it sticks.