Agreed. I am in the DC area, and was about to respond saying that the only experiment that would happen is how much of a mess 66 can surprise you with!
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In perfect conditions, it would take 40-45 minutes to get from Chantilly to the house, but 66 can be a nightmare in no time at all. Like you said, one car pulled over, a glimpse of a construction vehicle, or an actual incident and you can be delayed rather quickly. The road is such a mess that entire portions of the road are HOV only during certain hours (not during the time frame that JW would have theoretically been driving on it, but portions of inbound 66 are HOV only during morning rush).