So John walks up to the conference room. Looking at the schedule on the door, he tries to decipher whether or not it's open at the moment. After a few seconds, realizing that it would be easier to just check, he opens the door and peaks in.
Meeting interrupted.
So John walks back to his desk and continues to work. In the meantime, this same situation occurs again and again throughout the week.
Mike goes up to the door, sees the same schedule, and also tries to decipher it. Realizing that it doesn't make much sense, he goes back to his desk and orders a new sign holder, creates a standardized format for the signs, and also creates a red/green system to instantly show people whether or not the room is in use.
That extra 30 minutes of work accompanied by the vision on how to implement a system is essential in a bureaucratic area in which little annoyances multiplied thousands of times add up. The prior planning skill used in small situations such as this can also be applied to much larger and scalable situations.
(story and names were hypothetical)