Noah's army didn't have any choice. They had to investigate the outcome of the battle among rank 9 existences to develop a proper plan. They had a vague tactic that could lead them back to the other side of the Immortal Lands, but they still had many hindrances to consider.
The journey back to the first floating lake would take years, and Noah even planned to slow down that travel. His companions still had a lot to prepare, especially when it came to matters vital to the task.
King Elbas had to build inscribed items capable of stabilizing the collapse of the dimensional tunnel. They had to be strong enough to sustain the energy released by countless experts while fending off Heaven and Earth's external pressure.
The task couldn't require normal rank 8 inscribed items. King Elbas had to create something that bordered the ninth rank, which required his entire expertise, countless valuable materials, and a lot of time.