It is precisely in the everyday survival grind that a good business plan provides the business person the most benefit. Regular reviews of the goals, objectives, and interim targets bring everyone back in focus with what they are trying to accomplish. It provides a point of reflection. It redirects actions that have strayed. It facilitates proactive management of the chaos, rather than allowing the chaos to manage the company.
Business plans are for small companies as well as large.
The small company can benefit from even a simple plan that is prepared in earnest. To facilitate completing the plan, an objective third party can effectively guide a business through the process. Thus the company gets the benefits without the administrative burden. In the end, planning to open for business tomorrow is a plan. A good business plan just takes that process to a higher, more useful level.