I fail to see how you can conclude that God does not judge nations whenever it is necessary, as He has throughout all of history. There are consequences for sin and there are blessings when God’s Word is obeyed and/or His principles applied. Nations and individuals are all subject to the law of “you reap what you sow.” This applies to the individual as well as Nations. This is not only true throughout the Bible, it is true in secular history as well. I am a simple man Jack, and this is just simple common sense and simple common Biblical sense.
Throughout much of history you would have been correct in your assumption. But at the end of the age, which millions of Christians including myself believe to be now, God has promised to destroy all the nations except Israel . Therefore the world can no longer be viewed as this nation or that one being judged as needed. Now there are but three groups of people on earth; the Church, who will be delivered from the end times judgment (1 Thes. 1:10, Rev. 3:10), Israel, who will be preserved through them, and the nations of the world, who will be destroyed (Jere. 30:11).
So the idea of any one nation having a great revival and earning back God’s favor to escape being judged is obsolete. Individuals within that nation will be saved from the time of judgment, but all nations will be judged and destroyed.