After some prodding by one of my ad networks who noticed that I was asleep at the wheel I've probably more than doubled revenue from my existing traffic stream; all good.
One remaining item of indecision I have: does the panel think that should I move skyscraper ads (mainly/always) to the left as Google's heatmap suggests, or rotate them between right and left (slowly!) to help reduce ad blindness?
TBH, I haven't experimented for a while. But when I did, bottom line income was at least double with the left ad block. Currently I'm using a large rectangle on the left of my main index and that is a good earner.
However, Madsense changes very quickly and if I were to experiment again the results may be different now. As we know, what works for one site doesn't necessarily work for another. Only way is to have a play. But I do think the heatmap is a good guide.