For self-cultivators, besides diligence, the most important thing was talent. Many might disregard it, but actually talent might be the most significant feature of self-cultivators.
With more outstanding talent, one would comprehend techniques faster. That was why some could reach the level of Saint or Immortal, but some could only get to the Spirit Emperor or Supreme Realm after a lifetime of work.
What they lacked was talent, in other words, the ability to comprehend and learn. It was an innate ability from birth, the spirituality and perception related to one's past life.
Another way was by acquired learning, such as following a Saint or an Immortal, or eating some Saint Spirit Fruits to enlighten the soul and improve perception.
As for Qingfeng Li, he possessed both. He was the Sky Emperor in his past life, with prestige in the universe and peerless talent.