There were many groups that arrived after Wu Long's group had passed through the outer passages of the Ancient Ruin, but the furthest they could get to is the chamber where Wu Long did a service for the betterment of society out of the generosity and goodness of his heart.
Past that chamber the formations were still intact and no one could pass through, no matter what methods they tried, including the obvious brute force breakthrough.
By now most have given up, but there were a few persistent ones who returned on the 6th day and waited long into the night to see if they could still get anything by ambushing someone coming out.
Wu Long didn't feel like dealing with them now, as he would be fighting with them over the final treasure anyway, so they waited for the 'noon' of the 7th day when it would be time to move, consolidating their gains in the meantime.
