Really valuable post from ctanzio. But I too doubt that a 10C increase in temperature halves the cooking time. In my experience, it hasn't.
A lot depends on the amount of airflow and surface area exposure, since the amount of both will affect the oxidation rate, and oxidation of the resin majorly influences the color change. If you don't believe that, consider the color concentration improvement from concentrating all the color from a pale rosin into half its volume, alone. There would be little color change.