Think of an outline as a skeleton you must assemble bone by bone, gradually making it take form into a coherent whole. Or think of it as a puzzle in which you must put all the pieces in their correct places in order to see the full picture. Or think of it as a game of solitaire in which the right cards must follow a legitimate sequence in order for you to win. The more fully you can come to understand the outline as both rule-bound and creative, the more fully you will experience its usefulness and its power to deliver your message in a unified, coherent way.
This means, of course, that there are no shortcuts, but there are helpful strategies. If you leave a bone out of a skeleton, something will fall apart. By the same token, if you omit a step in reasoning, your speech will be vulnerable to lapses in logic, lapses in the evidence you need to make your case, and the risk of becoming a disjointed, disorienting message. When you are talking informally with friends, your conversation might follow a haphazard course, but a public speech must not do so. Even in conversations with your friends, you might believe they understand what you mean, but they might not. In a prepared speech, you must be attentive to reasoning in logical steps so that your audience understands the meaning you intend to convey. This is where your outline can help you.