I'd think Google knows more than any organization in the world how to best monetize a website. In fact uniquely positioned as the only company to know. Look at all the data they have access to. A lot of these people run g analytics too not just adsense. They give up their website data to g for free. If any organization has the hard data on what's effective and not, they do. Now, take their advice? That's a different story. I'll check industry standards if they say 3$ cpm and I'm getting 10 already, I don't need their advise necessarily.