I live in that area and typically have to leave my house around 6 on Sunday nights for softball games. I always do my best to take the back roads to avoid the flea market. Not only is there a lot of traffic at that time, those pulling out of the market are INSANE. They do not have any problem pulling out to the far lane regardless of if anyone is there or not. I've seen many accidents in that area. A-Train...how far north are you going on I-35? Try the 130 Tollway if you're going to Round Rock or further north. Yes, it's tolled, but it's 100x faster and safer.
Ditto. I'm off South Congress, and I use downtown to get around. Otherwise if I need to leave the area, I'll use Mopac to get to Barton Creek or to the Arboretum. Problem solved. I'd say living off Congress, I use less than 1/4 tank of gas a week.