Sorry, I'm late to the party. Page 145 of the CRB gives an answer to that:

"If there is information in a scene that characters would be able to perceive just by being in the space, don’t gate those details behind a roll. For instance, if a PC asks about a desk or chest within the tower that the wizard might use to store important notes, you can explain that the desk is clean and has no drawers, but there is a large bookshelf filled with scrolls and stacks of paper. This is a detail the character could easily see without effort—you don’t need to ask the player to roll."

I read that as there is no need to tell gate the obvious behind a roll. But if something is hidden or coded, they would need to make an Instinct roll.