The Rules No One Wrote Down

Think of the last person you hired straight out of school. Six weeks in, they asked a question anyone else on the team could have answered in their sleep. Who approves the budget? Whether "let's pick this up Friday" means Friday? Which meetings you can skip and which you never skip?

None of it was in the onboarding documents. Most onboarding documents cover the benefits portal and the org chart, and leave out everything a person needs to stop looking new.

What changed with the people coming in now?

More of them are telling you how they process information. In an April 2024 Harris Poll survey for Understood.org, fifty-one percent of Gen Z adults reported learning and thinking differences, against twenty percent of Gen X (Understood.org, Neurodiversity at work: Gen Z survey). Thirty percent of Gen Z reported a diagnosis. Forty-two percent had requested a workplace accommodation, and forty-five percent of those who asked were turned down.

The self-reported numbers are contested, and they should be. A report is not a diagnosis, and a generation raised on the vocabulary will use it more. Nothing that follows depends on the number being right. The fix is the same either way, and so is the cost of skipping it.

Why does an unwritten rule cost more than it looks?

Because it only ever gets tested on new people. Everyone who has been there a year passed the test long ago and no longer sees it. The newcomer who fails it rarely gets a correction. They get a reputation, usually a single word: careless, slow, needs a lot of hand-holding.

An unwritten rule is a test you only give to new people.

The word travels. It goes into the manager's head, then into the first review, and eventually into the exit file. What the record shows is a person who did not work out. What happened was a rule nobody had written down, failed by the one person in the room who had no way to know it.

The second cost is quieter. A new hire who gets marked down for asking learns to stop asking. The questions do not go away. They go underground, along with whatever that person noticed that everyone else has stopped seeing. That is how signal loss starts, in the first ninety days, before anyone has a reason to look for it.

Where does the cost show up?

In early departures and in the manager relationship, which is where the unwritten rules are enforced. EY's 2025 neuroinclusion study surveyed 1,603 neurodivergent professionals in 22 countries between July and September 2024. Thirty-nine percent said they planned to leave their jobs within twelve months. Line manager behavior was the largest single influence on whether they felt included (EY, EY Global Neuroinclusion at Work Study 2025).

That is one group, surveyed by a consultancy, and it is the group that pays this cost first. The mechanism in it is general. A manager running rules nobody wrote down has one way to enforce them. It is judgment of the person, which is the one thing a written rule would have made unnecessary.

Why do the rules stay unwritten?

Because the people who could write them down are the people who can already read them. To them the rules are obvious, so writing them down feels unnecessary. The cost lands on new hires, and senior people don't see it.

The Navy settled this a long time ago. A ship's captain writes standing orders, and every officer who stands a watch has read them. Nobody on the bridge at three in the morning is expected to guess what the captain would want.

I built explicit systems at the companies I ran for a practical reason. I could not read the implicit ones, so I wrote them down: promotion criteria published before anyone was measured against them, agendas out ahead of meetings, decisions recorded with the reasoning. The written versions turned out to work better for almost everyone, and they did not depend on who was in the room.

The same gap runs the other way, in what your longest-serving people carry that the organization has never recorded: competence nobody has written down.

Run it yourself

  1. Ask your three most recent hires, separately, to list what they had to learn by getting it wrong.
  2. For each item, check whether it is written anywhere a new hire would find it. Count the ones that are not. That count is your first number.
  3. Count how many of the people you hired in the last two years left within their first twelve months. That is your second number.
  4. Write the missing items down, put them where the next hire starts, and ask the next cohort the same question at ninety days.

If the list gets shorter, you have removed a test nobody meant to set. If the early departures move with it, you have a number to show for it.

What you could notice this week

Ask your newest hire one question: what did you have to figure out here that nobody told you? The first thing they say is usually the rule costing you the most.

I will be plain about where this stops. Writing a rule down does not make it a good rule. Some of what surfaces will be rules you would rather not defend in writing. It will not fix a manager who is the problem, and it will not keep someone in a job that was wrong for them. What it removes is the test nobody meant to give.

You now have a list most organizations have never made, built by the only people who can still see the rules.

What is one thing your last new hire had to learn by getting it wrong?

When the questions stop, the concerns usually go with them. The Signal Loss Check takes six minutes and shows where an accurate concern gets lost between being raised and changing a decision.

Sources

Peter Allen Mann spent thirty-seven years in leadership, including four years as a Navy Surface Warfare Officer and two companies founded and run, and is the author of The Perception Revolution and The Projection Fallacy (Fast Company Press). He writes about late recognition and the working life at peterallenmann.com.