On average, a good business plan will be about 15 to 20 pages. Keep it concise but detailed. A good business plan will pay dividends both in the short and long terms. An investor and/or bank manager will see this and if the plan holds up well, then this will bring you the business that you seek. And from a personal point of view, a great business plan is something that you can return to time and again as a good reference point - something that you can draw upon in the future.
Though the rate of failure is highly significant in small businesses, and it is the main reason why a good business plan is needed. Probably for raising additional cash and to provide potential investors and lenders with the information required to make investment decisions. This makes developing a business plan extremely important. One's business plan has to stand out and his projection has to be firm due to higher competition in attracting funding for his business. Investors no longer risk their money on businesses that do not prove to have great potentials for them.