I worked for a huge company with over 30,000 employees and as I was waiting for the shuttle to take me to the clinic for an illness, a co-worker came and sat beside me. I looked at his employee badge number and knew he was new, so I asked if he was going for his pre-employment drug test. He said no, that he had been tested for that 4 days prior and was pulled for a random. FOUR DAYS, out of 30,000 people. I was never tested after my pre-employment. It really is random. DOT.

Oh, and by the way... random because they "feel they need to" isn't random. That would be reasonable cause.