Why should I include a summary at the top of my answer?
You should include a summary at the top of your answer because it helps students quickly gauge whether your answer will teach them what they're trying to learn.
When a student is stuck on a problem or trying to learn a concept, digging through a lengthy introduction can feel frustrating and more confusing than helpful. By starting your answer with an overview of the most relevant information, you're letting the student know that they've come to the right place.
Summaries also make the most critical points of your answer memorable and easier to digest.