Randomization powered Security

Last week I read about an interesting move made by LAX to improve security by implementing a system called ARMOR. ARMOR which was developed at USC will help in randomizing the checkpoints and patrols and searches done at LAX. By this, the bad guyz wont be able to analyze and study the patterns of security measures at LAX and so their confidence level on clearing security would go down. I was actually waiting for Schneier to write a great post about this idea but he just referred to itis a "great idea". I found a reference to this paper published in 2002 talking about a similar implementation of randomization to improve airport security. Initially I was not able to understand as to how randomization could be better than a deterministic model / approach (which is currently in use at airport security systems) but the paper referred above was very useful in clarifying my ignorance.