It was a well-known fact that a cultivator could only master one type of intent. Attempting more than that risked disaster—the body could explode, become crippled, suffer qi deviation, or even endure all three at once. For that reason, cultivators rarely attempted it unless they possessed a unique physique that allowed it, such as Kang Huilang's or the Golden Nine Revolutions Cicada Physique, which granted eight clones, each with different attributes and talents.
Physiques like those could make it possible to master multiple intents. But even then, Kang Huilang's case was exceptional. The Golden Nine Revolutions Cicada Physique spread the burden across separate clones. Each clone was essentially a different body, and so the fundamental law of one intent per body still applied. Kang Huilang, however, could learn and host multiple intents within a single body.