Muad' Dib often made great use of prescience. As far as I understand, he literally saw parts or threads of the future. Even though he couldn't grasp everything, he'd consciously chosen to avoid certain scenarios and he had let bad things happen to him if they led towards preferred scenarios.
In contrast, Leto II seems to be almost completely blind to the future. His affair with Hwi Nori, not predicting all the ambushes and rebel actions...
What happened? Is Leto II somehow less potent? Did he deliberately decide not to use such powers (in that case, how can he know he is indeed leading towards the Golden Path)?