My pattern model has a 12 oz tank for the 1.25. I fly from half to almost full throttle most of the time. I usually land after 10 minutes with slightly less than half a tank of fuel, depending on weather conditions. I have seen it use less than half a tank with 11-13 minutes of flying. I would not worry about flying 15 minutes and still having plenty of spare fuel onboard. I've considered changing out the tank for a 10 oz one.