One of the major issues I'm coming up against at the minute is the view through window though. When combined with a multi-channel strategy, and retargeting, view throughs can just inflate numbers, masking true effectiveness.

I've lived my life doing digital advertising work, but if I turned off 3/4s of ours tomorrow, I'd be loathed to pin my cap and predict volume would drop by that.

Interestingly, I've seen a lot more focus on different attribution models recently, I think people are finally asking the questions now it's been ingrained in a lot of teams for a few years.