The king and Maria's team already found many of those strange symbols present on the fourth floor. But the problem is that destroying those symbols is becoming harder. It looks like when they destroy one symbol, the dark energy present in another symbol will become denser and it will create a more powerful barrier.
Because of this, destroying those symbols is becoming harder and harder. That does not mean they would stop trying to destroy those symbols. The main problem is that if they continue like this then it will take them much time to destroy all the symbols present on the fourth floor.
They would not be able to divide their team more than that. Because even both of their team almost took 30 minutes to destroy one barrier. Like this if they divided the team more than that it would take much time.