internet marketing

Last week I thought I knew something about marketing. I met with a client about their Google Adwords campaigns and we discussed making some changes since we needed to set their ads apart from the competition.

After I brought everyone up to speed on how Adwords work, one of the senior members of our meeting said "We should make two ads per campaign. After a couple of weeks, we check the click through results and tweak the under performing ad and repost it as the new second ad." I said "Wow that sounds like a good idea". He told me that it actually is a very common practice called an A / B split testing that they use with post cards and direct mail all the time. Why wouldn't it work in this case?