A good business plan would document short-term and long-term goals of the business and establish specific tasks for achieving theses goals. Planning is the process that never ends for a business and is extremely important in the early stages of the business. However, business planning and is extremely important in the early stages of the business.
I say that because of course you need to be careful with commercially sensitive ideas, as you do not want to pass your plan on to someone in the pub who then starts your idea before you across the road.
I teach that you should seek to learn from competitors; obviously never copy another business's idea or what they are doing, but you can absolutely learn from their mistakes or see what they are doing and discover ways to improve it. All of that analysis belongs in your business plan: make sure you have your competitors under the microscope and make sure that is a solid chunk of your plan. That is some of the best research and information you will gather about what will make your business successful in future.
A business that makes sense and is going to be sustainable in the future is one that has that clear vision within which all the smaller parts contribute to make it successful.