The life inside the separate dimension wasn't easy, but many adapted faster than others.
The human cultivators had it easier than most. They had to deal with their lack of freedom, but they didn't have a hard time training. After all, they only needed "Breath" and some fights to strive for the heroic ranks.
Instead, the situation wasn't easy for the heroic cultivators. Their requirements to advance were harsher, and the peaceful life inside the dimension made their growth slower.
Some talents still managed to improve at a decent pace, but they also suffered due to that stale environment. The separate dimension didn't offer any incentives, so they could only rely on their willpower to keep growing.
The hybrids had it worse than everyone else. They usually required a lot of food, but that was one of the most valuable resources inside the dimension.