The location of the enemy's main camp, known by all the trial takers within the cave, was quite evident, thanks to the enormous flag in the sky.
However, despite this knowledge, not a single soul ventured in that direction in those days. It was obvious that the enemy camp was teeming with soldiers. To take down more than ten soldiers, they needed to join forces.
With dozens of people in the camp, it required teamwork to divide and conquer, in order to systematically eliminate all the soldiers within the camp.
At a time like that, rushing towards the enemy's headquarters would have been nothing but suicide; there wouldn't have been any other outcome.
According to everyone's thoughts, they needed to at least reach the Aperture Tempering realm to confidently maneuver among the numerous soldiers and seize the opportunity to assassinate the enemy's leader.