Writing a plan before starting an essay or project is always a good idea. It can help you formulate ideas and ensure that the structure of your final essay is appropriate and logical.
Essay plans can also be used to remind you of important points that should be covered in your essay, as well as highlighting the final structure. This is particularly relevant to exams, where it's all too easy to forget details as you hurry to write without a plan.
Plans do not need to take up much time, as you can use keywords and phrases, make notes of important references and logically order it within 5 - 10 minutes. Planning also makes sure you have read the essay question carefully. Just rushing in can make you forget the question, or answer the wrong one. Planning gives you a minute or two to consider what you are being asked to do and make sure you fully understand.
An essay without a logical order, and a beginning, middle and end will automatically score lower. An essay argument is supposed to be coherent and easy to keep up with. If you run out of time, an examiner should be able to look at your plan and see clearly the approach you were taking, and the order that you were putting it in, as well as your key points and references.
If you are not in essay conditions, planning work allows you to find out which words you may need to define, and find out what you could research to make your argument stronger. Even a quick brainstorm can count as a plan if you link the points you want to use into an order. Make sure you eliminate anything that is irrelevant, and have gathered related ideas under one heading.
Having a plan also allows you to show your preliminary response to a question and ask other people what they think. This could help you formulate your counter argument to their opinion, as voicing your opinion out loud makes arguing your point much easier.
It is often recommended that you write your titles, your headings and your outline before you begin writing. This is so that your writing is definitely being directed the way that you want it to go, and stops you risking going off course. Producing these titles and then jotting information underneath will count as a plan, and make writing your first draft so much easier. It is a lot easier to focus if you have something to keep you on track.
To sum up, it is very important to plan, no matter where you are. In exams, a well written plan will only take ten minutes but will help you to gain points if you run out of time. It will also make sure you understood the question, help you to form a structure and remind you about key points you want to use. For important projects or essays, they allow you to produce a preliminary response, ask other people's opinions, and do additional research. Writing without a plan is not a good idea, and most institutions will expect to say an essay plan as well as the finished document.