Perhaps it was because of Ling Tian's constitution, perhaps because he often studied cultivation techniques and secret manuals, perhaps because he had nine golden cores in his dantian and also cultivated his heart, or perhaps because the secret arts he had mastered placed great demands on his mental strength. Whatever the reason, as his cultivation improved, the pace of his mental cultivation didn't slow by much.
Other cultivators grew slower and slower as their cultivation advanced. Breaking through a minor realm often took hundreds of years, or even longer. Ling Tian, however, needed only a little over a hundred years. His Mental Cultivation had now reached the peak of the late Golden Immortal stage, and he could break through to the Golden Immortal Great Perfection stage at any moment.
Hua Min'er and the other women had only reached Heavenly Immortal Great Perfection in their Mental Cultivation. They were far behind Ling Tian, and as time passed, the gap between them would only grow. So by the time Ling Tian reached Grand Unity Golden Immortal Great Perfection and ascended to the Immortal Realm, Hua Min'er and the others would still need a long time to reach that level.
The same was true of Hua Min'er and the others, and of Zi Yun and his companions. Reaching Ling Tian's requirement would take them much longer than it would take him. With that time, Ling Tian could accomplish many things, such as finding a safe place to settle.
It was precisely because everyone else would reach Grand Unity Golden Immortal Great Perfection long after he did that Ling Tian had issued such a strict order.
Hua Min'er and the other three women quickly understood Ling Tian's intention. So they could reunite with him sooner, they decided to leave their clones behind to cultivate