I'm not super familiar with metro out that way but there are definitely longer distances between stations once you get out past Ballston.

I think it might have some closer together for the bigger areas like Tysons and Reston, but similar to the East Bay with BART in the SF Bay Area, the further out suburbs will be set up to require people drive and park to each station from that surrounding area for long distance transit use only versus using it locally for super short micro trips in the major city centers (DC and Arlington).