That would, in my opinion, be a good way to improve your analytical skills prior to your Economics trial exam and will definitely allow you to break questions down into their important parts as well as determine your main points much more easily during the actual exam. However, I believe such a strategy should be implemented once you're confident about your knowledge of the content so that you can maximise the effectiveness of your essay plans, meaning the emphasis should be on your knowledge of the content, with the essay planning tactic subsequently complementing your preparations.
I hope this helps!
