Before digesting the gains from this time, Zhou Tian was not ready to immediately start a war with other monsters. The pioneer gets the most gunfire, even though Zhou Tian currently does have enough power to trounce the Lord. But that doesn't mean he can disregard all monsters and arbitrarily annex their territories.
The Corpse Demon, who held some grudges against Zhou Tian, is a case in point. In terms of power, the Corpse Demon is definitely not weaker than the current Zhou Tian, and even if the other party could break Zhou Tian's spiritual attack, its chances of winning would be greater than Zhou Tian's. However, with the power of that Corpse Demon, it is still being held back by the other monsters, preventing it from expanding. If not careful, it may even be annexed by those monsters.