I couldn't agree more. This has become one of my biggest pet peeves. Once there is a predictable pattern to the "random" searches it is no longer random and defeats the whole purpose. I've taken to doing what you and others did, waiting for a victim to get snagged and then boarding. It's really too bad that most of the new security measures are just cosmetic to make someone, namely the ignorant flying public and the politicians, feel better.
Thanks for the opportunity to rant.
Doug