Nah, wasn't part of that convo last chapter, but his predictions are always right. You are forgetting that his entire gimmick is that he got a high enough intelligence stat from his job change, that he quite literally predicts the future months in advance. If something like a fight could end up with a different result than he expected 2 minutes before it, then there would be tons of stuff outside his cognition that occur differently from how he expects, every few hours. Which would quickly butterfree into his predictions being no more accurate than a sharlatan roadside fortune-teller, ala chaos theory.
So we know he is never wrong both because of it being his gimmick (so author can't undermine it without undermining the entire story) and through empirical evidence that can be derived to something akin to omniscience.
If he ever claims something different, he is obviously just lying and we are just lacking the perspective to know it as it is a story told in 3rd person.