I think its much more about how effectively you use your forces not how much you send, especially in this war.
First campaign you send what you can send a campaign later you can fight with all your army.
Don't think that by simply sending everything you have you can defeat Aurvendil at all.
You have a much larger
chance to win if you attack with a larger force. Usually, in battles, the large force wins, unless the environment plays a big role (like walls or terrain.)
It would be more efficient to take your entire army and attack in one go, for the price of another month, with greater odds of success. This, rather than attacking in waves with pockets of forces, having them all die or take heavy casualties, which would then force them to retreat and refit all the way back home.
