The three dueling grounds were scheduled to be traded for a spot near the center stage as officials got ready for the regional winners. The break between the end of the third semi-final and the beginning of the last tournament matches of the day was only as long as it took for staff to quickly prepare the new circle.
That act was also, in a way, a showcase of those who focused on non-martial pursuits. The supporting mortals and cultivators that would later strive to repair or plug holes in fortress walls while others fought off assaults of Voidlings.
Fundamentally, the construction of the whole 'temporary city' of the competition grounds was meant to show the human capacity to build quickly. It just was not as 'exciting' to think about this factor as it was the warriors that prevented your death. While everyone had different requirements to be roused and thrilled, weapons expertly clashing simply ticked more boxes than bricks being laid.