An instruction written for everyone should be understandable without an insider nearby.

Instructions written by people who already know the system tend to assume the reader knows it too. A step is skipped, a term goes undefined, and the result works fine as a reminder for insiders and fails completely for the person it was ostensibly written for.

Give anything you write to someone with no background and watch them follow it without helping. Every place they stop is a defect. It is uncomfortable to observe and it is the only reliable way to find out whether the instructions can actually stand on their own.