I currently run one Adsense ad block per page on almost all of my sites. I have a couple of sites with a second block just above the fold in the center of the page, but those ads don't seem to ever perform well.
I'm considering doing some more experimenting with multiple-ad blocks per page, but previous experience leads me to think that I won't increase earnings, so I'm hesitant to spend the layout time to do it right, statistically speaking.
For those others who have tried multiple ad blocks on the same page, has anyone tried to get the ad blocks to be on different topics?
1. It seems (based on previous posts by others and my own generalized experience) that Adsense weighs text close to the ads in the page html higher when targeting the ads to the page content.
2. The biggest problem with multiple ad units (besides layout issues) seems to be that the second or third ad unit tends to get the lower paying or lower CTR ads on the page topic, or no ads at all if inventories are low.
If those assumptions are correct, then if you have a lot of content on a page, would it make sense to place the adsense code inside the html in such a way that the multiple ad blocks were near as divergent of wording as possible? Could that possibly create a situation where the different ad blocks were targeted to different enough topics to not affect each other in terms of available ads?
In my own case, most of my pages are "content-rich", in the sense that they have lots of text that cover multiple screen-fulls, so I could do some placement playing within the html, especially since I use CSS for layout and page location.
Anyone have experience they are willing to share with the rest of us on those two assumptions?