Yeah basically, it’s the Li Zhong/Jian Zhong comparison. It’s not that you’d never use the two together, but you’d often want to make the choice whether, for example, loose stools are due to cold damp earth with wood not controlling (GJ), or excessive wood on earth creating too much movement (BS). Combining one formula based around the former and one with its highest dose of the latter would need careful consideration, but is not absolutely impossible.