Credibility of the Omens

In chapter 1 of Rituals of War, Zainab Bahrani discusses the different types of omens that the kings would pay attention to before going to war. In King Hammurabi of Babylon, Van De Mieroops talks about how they would examine the intestines of sheep and would sometimes repeat the process until the answer was favorable. In Rituals of War, however, the Bahrani mostly talks about omens from the activities of the moon, such as eclipses. These events of nature have an element of surprise and cannot be repeated, unlike examining the sheep's intestines. For these reasons, these omens can only have one interpretation. What's interesting is that most of the time these omens came true, such as Teumman getting an eye and lip problem right before the war and then getting beheaded by the Assyrian king. This struck me as quite shocking because these omens seem to be very accurate, making them very credible. However, how was it possible that the oracles almost always gave accurate predictions? Were the omens really interpreted before the war and then lived up to? Or did the scribes write down the interpretations of the omens on annals in retrospect, and corrected those interpretations that were incorrect? It just seems so absurd to me that these omens were almost always accurate and that the kings believed them with such certainty.