Preparation is important, but raw power is vital as well. Preparation is not enough to kill Hercules or Gilgamesh. Winning is the goal of the war, and without beating those two powerhouse servants, you won't win. That is the reason I believe that this war and the succeeding war are not much different in terms of winning. It does not matter if most of the enemies are weak. As long as 1 or 2 monsters are there, victory is hard to get.