Last month, I decided to conduct a little test with my ads. I used to have five ads on each page. I spaced it out so that it wouldn't really make the page hideous. I still wanted the page to look cleaner, so I opted to remove two of the ads, leaving just three on the page. Strangely enough, my ECPM doubled once I did that. Is that normal? Has that happened to anyone else?
My third advertising network just increased their eCPM. All three are performing really well. Best I've seen it do.