In fact, I think this HBR article is the other side of that coin when it says you should write down the unwritten rules of the company. Aside from pulling assumptions out from behind the curtain given them some sunlight, the exercise is a great way to reveal how you company really reacts to stimulus. I’d take it another step further and say that the unwritten rules of the company are more the culture of your company than what HR says it is, thus making it ripe fodder for employer branding architecture and narrative.