The Fewer Ads the Better

When Google raised the ad block limit from one per page, to two, and then later
to three, many marketers decided it would be a good idea to go ahead and max
out the number of ad blocks on their pages.
That was not a good idea and many of these marketers have suffered from it.
It is important for you to remember that when you publish Google AdSense ads
on your pages, Google is effectively syndicating their Adwords ads, which is a
pay-per-click advertising network.
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What that means is the ads at the top of the page are there because the
advertisers for those ads are paying more (for the better placement) than the
advertisers with ads at the bottom of the page.
What this means to you is if you max out the number of ad blocks on your page,
you will go from having 4 ads to having 12 ads. This is assuming that you are
using the large rectangle ad block. The math: 4 ads per ad block and 3 blocks
equals 12 total ads.
At first glance you might consider this to be a good change, one that should be
more profitable for you, right? After all, the more ads you have available the more
chances you have of getting a click. Seems to make sense, doesn’t it?
Actually, it is not a good thing for you because it can very easily and very quickly
cut into your profits.
Why?
My tests in this matter have shown us that not only do we get fewer clicks the
more ads we have on a page, but we also earn much less for every click that we
do get.
we decided that this only makes sense.
If the top ad on your page pays you $0.50 per click, there is a very good chance
that the bottom 4 all pay less than $0.15. In essence, by increasing the number
of ads, you are trading higher-priced (higher paying) clicks for lower-priced (lower
paying) clicks.
We tested several pages of my own and decided that 4 ads is usually the golden
goose. However, this is not a hard and fast rule that must be observed at all
times. Occasionally, a 2 ad block pulls the best combination of earning-per-click
(EPC) and click-through-rate (CPC) which is exactly what you want.
My advice is if you're using more than one ad block on your page, test that same
page with just a single block and careful keep track of the results. Odds are you
will make more money by decreasing the ads.