With NASA, I believe it was 4 25 minute sessions, and the traffic was not bad. Not as much time as chin, but still pretty decent giving you 8 sessions over a weekend.
Have you ever considered tracking out west? Spring mountain in NV is hbome to a huge group or Radicals and even has a Radical Loop configuration. My company is holding a race out there later in the year, and looks to be a great track.