I noticed a comment under last week's map lesson from a student who suggested that we could ignore maps because they are much less common than graphs and charts.
While it's true that graphs and charts are the most common types of question, I think it would be very unwise not to prepare for diagrams and maps too. What happens if you get one of these questions in your test and you haven't prepared for it?
Another point to note is that diagrams and maps are really easy to describe if you know what you're doing. Taking the time to study the lessons I've written about them could turn out to be a very good idea.