It almost like people don't understand what a thermostat does. If it is 90 degrees in the cabin and you set the controls to 70 you will get full cold. Turning it to 50 degrees you still get full cold, but now you will be freezing everyone somewhere during the climb out. And wildly overshoot to cooking the people as you try to defrost the packs. First leg, set to 11 on the ground, 12 once airborne, cruise adjust to 20C duct temp. Next leg, remember that setting.