To shuffle or not to shuffle

When moving on to the next area, do you shuffle the 8 previous cards into the deck before dealing again? Or do you keep those on a separate discard pile, while the main draw pile is completed in order?

I’ve been shuffling everything in between, but this doesn’t seem to make sense for the Crow/Raven Overview ability… If I view the top 2 cards and place them in the deck wherever I want, what’s the upside if I shuffle before the next time I deal?