If you don’t have a specific immediate need to show a formal business plan to a banker or investor, then you are probably better off doing just a lean business plan, for your internal use only. To make the best impression on banks and investors, your business plan outline should be presented in the standard business plan format.
Start from the very beginning understanding that your business plan ought to be specific to your business needs and objectives. Every business ought to have a plan, but not every business needs a full formal plan with carefully crafted summaries and descriptions.
Developing your business plan helps you to step back and look at what is working in your business and what you can improve on. If you have employees, the planning process can be a good opportunity to seek their feedback on possible ideas and improvements. Your employees will value this opportunity to contribute to the business.
Your business plan should present what a banker or venture capitalist expects to see, in the order they expect to see it in. Following a standard business plan outline will keep you on track, and save you from botching your best chance at getting your business funded.