The world is such that often many 4th grade sects strive for over a dozen generations, yet might never have the chance to be promoted to 3rd grade.
Below the True Lake Realm, a cultivator's cultivation consists mainly in the continuous increase of their own cultivation. As long as one has enough aptitude and resources, it is not too difficult a task, but advancing from True Lake to Divine Sea is a huge barrier because it involves the transformation of the psyche.
There are many cultivators in the Divine Sea Realm in the Nine Provinces, but these are accumulated over generations. For a sect below 3rd grade to give birth to a cultivator in the Divine Sea Realm is often as difficult as reaching the heavens.
