DON’T SPLIT TEST ADS! Google weights the ad copy in addition to the keywords selected when determining the theme for your content network campaign. So when you include a second ad in one ad group with different text, you’re telling Google to assign your ads to different set of sites. This not only can cause you to lose your already performing syndicated slots, but changes the testing environment dramatically therebye invalidating the test. To “split test” an ad, make a separate ad group with the same keywords in it.
DON’T EVER TURN IT OFF! Turning off a successful /profitable content network campaign, seems to cause Google to do a kind of “reset”. You lose your syndication slots, and your cost per acquisitions can go through the roof. Lower the campaign budget to $1 ad day as opposed to shutting it off.