Allen after coming inside of the Dungeon killing those monsters continuously. You can say that all this time he realized that most likely he will meet the Boss monster today or tomorrow. As you know every time the same thing happens when the boss monster appears. Suddenly the number of those monsters begin to decrease and because of that, there will be a time when you won't be able to find any Monster and you should realize that the Boss monster already spawn in the dungeon.
So he actually can see the number of those Monsters already decreasing very much compared to before. Well he stops thinking about those unnecessary things and then begins to kill those monsters. Even though he could only see a few of those Monster present inside the dungeon but then again, it naturally take some time for that Boss monster to appear on the Dungeon so before that he wanted to kill as many Monster as he could, so he could also able to gather resources from those Monsters.
