The Bank is a fortress....yeah right..!

We're told that the bank in El Paso is a fortress, better than the bank of San Fransisco..
When the bank is closed, an armed guard always remain and a patrol is outside..!
Well, the 4 men patrol all walk together in the same direction.. basically.. leave the front and sides unguarded when they move around. If they wanted to make it more safe, they should of had all 4 guards walk in different directions and cross each other during patrol.