A clear, concise and résumé is a sign that you have studied the subject.
Explanation:
When you can explain some of the main ideas on some subject and can explain them in a brief text or, orally, in a short period of time; that means, when you can be concise, precise and yet very clear, it means you have a great knowledge on the subject. It means you have the concepts very naturalized and you find it easy to explain it to others.
