6 hours is not bad. I just had a 5 hour layover between a 2 hour flight and a 1 hour flight. More time laying over than flying.
And remember, it will take you 30 minutes or more from gate to outside at Dulles (you have to catch a bus of tram to get to the main terminal). And yuo need to get back in time to go through security again, and to get the bus/shuttle back to the proper terminal/gate.
And it was NOT a lack of reading comprehension, but a failure to read the entire post before replying.