Writing a business plan is the first step to launching a profitable business. The length of your business plan does not determine its effectiveness in guiding you to achieve your business goals. Nope, it doesn't matter if you write a paragraph on a napkin or a doctoral dissertation. What determines the effectiveness of your business plan is what you do with it.
A Leader that works on the business guiding a team to achieve an established vision versus working in the business i.e. hands on in producing a widget or doing the actual hammering. By working on your small business you are in a better position to lead your organization through its mission, goals and strategies.