I have no doubt that I could increase my CTR and income by following the heat map better. But I'm not willing to sacrifice my page layout for the money.
That said, I have found that I could use adlinks very effectively in hot spots without screwing up my layout. It's just the difference in ad sizes between adlinks and regular ads that makes that possible for me.
But the main point is that you can put either money or users first.
My opinion about which is more profitable is that putting money first will work better in the short term. Putting users first works better in the long term.