When we learn the Torah, we work off the assumption that as the Torah is directly from Hashem, every word and even letter is there for a reason, and a lot of commentary and even Halacha is based on this.
When we learn Nach, do we also apply this principle and is it to the same degree? Neviim is written by other neviim, but they weren't as great as Moshe Rabbeinu, and Kesuvim weren't written by neviim at all.