I just finished my installation using 0.5mm wires (not sure AWG ratings), they are sold as alarm system wires, indeed the maximum distance between controller and the farthest valve in my case is only 15m (under 50 feet) and the valves are RainBird DV series 24VAC.
Everything worked perfectly during the test phase, I will start a full irrigation program in a couple of weeks if you need more feedback.