That's the beauty of the combination of flat bars and aero bars. In traffic or approaching intersections, you'd use the flat bar, with all the controls in their familiar places. Once you're away from traffic, you use the aero bars.

Come to think of it, in areas where I want the security of having a hand near a brake lever, I spend a good proportion of ride time with one forearm and hand on the aero bar and the other (usually the right) on the grip of the flat bar. That way, I can brake and shift while still supporting most of my upper body weight on the forearm pad. (Sounds complicated, maybe, but very easy to get used to.)