I've read some opinions on here that reducing the number of ads on one page would increase your EPC because there would be less ad space and Google would display higher earning ads on your site. With 3 ads, there would be high paying ads and low paying ads so visitors clicking low paying ads would lower your CTR. I didn't totally buy into this idea as I wasn't sure Google would exactly display higher earning ads in the one box. So i decided to test it on a section of my site. I had previously run 3 ad boxes and 1 ad links box and set up channels for each. one of the ad boxes and the ad links comprised almost 3/4's of the earnings for those pages so I decided to try and reduce the # of ads to the highest performing ad box and the ad links. I had actually only run 3 ad boxes and an ad links for 7 days and I've reduced the number of ads to 1 ad box and the ad links for the past 3 days so take this for what it's worth. For me, EPC on the ad box actually went down from when I had three ad boxes. CTR on that box rose slightly but my CPM for that ad box dropped from when I had displayed 3 ad boxes. For the Ad Links, EPC rose quite well but CTR dropped on the ad links so CPM was only slightly higher than when I had the 3 ad box configuration. Total earnings for that section of my site have dropped and it would take a substantial gain in EPC (considering the same CTR) to earn the same amount so I think I will move back to 3 ad boxes. Actually, 2 ad boxes and the ad links comprised for over 90% of earnings on that page so I think I will try that out next. Like I said, I only tested 3 ad boxes for 7 days and 1 ad box for 3 days so my timeframe for testing has been pretty limited. From the initial results, I really don't foresee making more or even the same amount b/c I haven't seen an increased EPC to make up for the lost 30% of earnings from the 2 other ad boxes. Sorry if this was a little confusing. I'm not saying this doens't work... it's just that it didn't seem to work for me.
I think a lot of this depends on what the page looks like. if you have a long page putting one ad up to, one ad in the middle and one ad at the bottom makes sense to me. If you have a short page and you can see all three ads without scrolling, I could see how your overall earnings might drop. What is the setup on your page?
The pages are mostly long but when I had all three ad boxes and the ad links up, you could see 2 ad boxes and the ad links without scrolling down. I think for me, it was just a matter of the other two ad boxes comprising about 30% of my total earnings. For me, EPC would have to go up by more than 40% just to make the same as before and this didn't happen for me. I've now put up the second best performing ad box that previously comprised about 20% of earnings and will probably keep it like this in the long term. I'll let you all know how it compares.