I should also mention that you might want to look into a Deck Saver. It’s a little bit of plastic you can 3D print that fits into the original Deck case, and it will hold your device in place in the event you pick up the case with the lid open.

If you don’t want to bother, I have a rule I follow: if the Deck is in the case, the zippers go shut. First thing. No exceptions.