Modern herbal curricula have come to categorize Guizhi as an herb for the common (external) cold and Rougui as a key material for the treatment of (internal) yang deficiency, thereby greatly limiting the wide range of applications ascribed to cinnamon in ancient times.
Stacked Rougui from 20-30 Year Old Trees in Hekou, Yunnan. Image sourced from Classical Chinese Medicine. Available at: https://classicalchinesemedicine.org/wp-content/uploads/2013/06/guizhi-rougui23-500x333.jpg