I acquired that bit of faulty information a long time ago, so maybe it was different close after 9/11? Or it was just never really true in the first place?
Related to current events, and maybe you know this already -- after 9/11 they changed the allowed flight paths around National such that every inbound flight is basically doing a canyon run over the Potomac. I'm willing to bet that was a contributing factor to the recent crash.
I used to fly into National every two weeks, for about three years. Landing pattern was always a trip, 737 making real tight turns for a commercial airliner.