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.
Everyone has prepared a business plan. Well, should that read, everyone should have prepared a business plan? My thinking is that these tend only to be prepared when they are needed, rather than as a useful business tool for all senior management. My top five ingredients are: 1. Understand what a business plan is; 2. Understand what you intend to use it for; 3. Identify and implement the critical steps to achieving a successful business plan; 4. Understand what needs to be included in the plan; 5. Be aware of gaps or weaknesses in your plan.