i have implemented section targeting into my HTML for better targetting of my Adsense ads. It's been running now for weeks, and i don't see any better results than before.
what he is trying to highlight, is that with Google you can't really trust their SEO tips and tricks. At the end of the day they are there to make money.
with regards to your query, I stopped my section targetting as I found it not converting in any way, I am getting silly traffic and I end up paying alot for nothing.