You probably know about many of the failings of the human brain. Here's two:
1. You'll know that the memory is flawed, and we only remember the extra ordinary. So we only remember the times a train was early or late, not the majority if times the train was on time, so the memory thinks trains are 'always late'.
2. You'll know about confirmation bias, where filter out information that conflicts with our beliefs and pounce on the stuff that reinforces it. So immigration can be good or bad, depending on what you believe.
Yet when it comes to the job, we seem to forget all this.
How else could 95% of advertising be utter dross, the ordinary that no one notices? How else could it be that any category has most of the creative work looking exactly the same, and put in the same media at the same time? It's the everyday vanilla.
Why else would we pounce on the IPA Databank? A small sample of work that is there because it was believed to be effective and someone has spent the money to prove it? 90% of our output is not in this, because it didn't work, or the evidence doesn't fit IPA requirements. We jump on stuff like 'Fame and emotion are the most efficient strategies' when actually, it's more like, the rest of what's out there is so bad, doing stuff that is simply not the equivalent of trains just being on time, average, not noticeable, works. Go Compare's singing tosser works because you might hate it, but you can't ignore it. But we leap on the evidence that fits our belief that creativity and 'great work' is the only game in town. It's incredibly powerful, but the uncomfortable truth is that the DFS ads we all hate actually work.
How else could you have compelling arguments that TV advertising no longer works, and equally compelling arguments that it's become more effective? Confirmation bias, that's how.
I get bored with people using John Lewis Christmas as evidence that TV, Fame and Emotion work amazingly. When they happened to work IN THIS CASE.
Just as I get bored with folks citing that Pepsi in the UK shows how TV ads are a waste of time now, it's all about video and social (it was in THIS case, it won't be in another).
By all means, use the evidence that's in the sweetspot of what you think the client should buy to make money and what makes you money (awards, big spend etc) but don't believe your own hype.
Put another way, if you tell enough untruths, or let's be kind, selective truths you eventually believe it yourself.