I have read this question and the answers, but I am still puzzled about the topic of the subject line. Let me phrase the question a little bit differently:
In the introduction of SECTION I: Mapping, the instructions explain that the task is divided into 7 steps, the 6th step being “Create a script that automatically saves maps”.
Then in the detailed instructions that follow, only the first 5 and the 7th step are elaborated, the 6th step being left out.
In all the material which has been covered leading up to this, we have never learned of a need to automatically save maps, so I am wondering if the 6th step in the introduction is incorrect and the detailed instructions are correct.
In the unit 2 - Map Creation, in 2.4 Saving the map you learned how to save a map manually. In this exercise, we are asking you to apply that knowledge plus other knowledge of ROS basics to save the map automatically using a script.
Applying theoretical knowledge to practical applications would often require that you pull together different bits of knowledge from different topics, and the project is trying to prepare you for that. The theory for a single topic can hardly cover all the needs that may arise in a practical situation.