Why? Why is that space necessary? It separates the advertisement from the content and since it's random, there's nothing we can do about it. I don't know how much of a difference this extra space actually makes, but I definitely don't think it helps. Here's the way it should be. Is anybody else bothered by this?
It is a very little space, isn't it? It appears because (IMO) more ads to display in large reg. Maybe you should consider yous half banner twice ( for one ads ). I didn't try it yet whether if it display different result or not. If you have tried that pls tell me
Sure, it's little space. However, even the smallest amount of space can give your viewers the idea of an advertisement or unconnected content. This of course means less clicks. Also, I have tried the 336x280 and the 300x250 and both do the same thing. It really all depends on the site and the ads Google pulls that are relevant to the provided content. I would try an ad smaller, but the smaller you go in ad sizes, the less clicks you will actually receive.
But those clicks where two ads are displayed in a large rectangular ad pay more than 4 ads rectangle.
In my view, you should not really worry of the things you can't control... Everybody wants maximum number of links to be showed, but thats how Google is designed to provide random number of ads, sometimes you may get only 1 ad in that whole block What you can control is Ad Placements and Using High Paying Keywords?
Now thats an interesting point. I wonder if there is any difference in CTR between sparsely populated and thickly populated ads.