I would say that on the first go, you form a basic understanding of what you experience. And once you understand something, you ignore it (even if that understanding is wrong or incomplete).

This gets you stuck in a state where your understanding is a bit shallow, you have gained a shallow understanding and now just immerse yourself, instead of seeking further understanding. And without that further understanding, experiencing the content always feels novel.

But the second time, your brain has to refamiliarize itself with the content - this time supported by everything your learned last time (no longer content with staying ignorant because of constant exposure). And this is when the deeper patterns that before created immersion (by staying hidden from your mind), now become predictable (resulting in boredom or frustration).

This also means that if you want to figure something out in depth, you have to take long breaks. Otherwise you ignore the 'obvious' parts (never fully exploring them), and get stuck on what you decided are the 'obviously relevant' parts (which they might not be, or may only be a subset of them)