Because the difficulty of surviving, sustaining, and progressing in the Beast Domain only grew higher the deeper they went, their journey stalled significantly. Of course, while it got harder, it naturally made them stronger.
Rui forgot what protection felt like during this time.
He forgot what safety felt like during this perilous voyage through the Beast Domain.
The fourteen months he had spent under constant protection from Martial Masters might as well as have happened ages ago. While he previously felt like he was stalling and growing rusty due to the lack of danger that served as a crucible to forge Martial Artists, now, he felt like he was perhaps in too much danger.
It shook any rust he thought he had accumulated off him.
Now, he had very naturally learned to grow an eye at the back of his head. A state of subconscious alertness in every inch of his environment was absolutely necessary and naturally came.