Since I don't two step, I would brush. I can get a good job brushing faster than I can soaping and rinsing. The secret, as always is making sure the soap doesn't dry. In the summer, here, that is very nearly impossible.
So, I would do what I do. I would brush the cab, wash out the wheels, and finish the windows. I can do about 10 to 15 daycabs an hour doing that, and it will make my expected margins. Our record was 75 daycabs in 3 hours. We were moving and grooving to get it done, though. I think that it was the steak dinner I promised everyone at the end of the day...If we got done on time.