In serious cases, life is in danger due to self-contradictions.
It's like cultivating multiple secret martial art techniques at the same time, with completely different directions of physical cultivation. One requires lightness, the other strength and defense. So, how should the muscles develop?
Such a practice will only result in a sickly and distorted creation.
That's why, Sheng Feinan rarely hears of fighters possessing multiple qi at the same time. As for what he just said to Casio about cultivating the Holy Water Absolute Art, it was a momentary slip of the tongue due to exhilaration.