The benefit of strategic planning is that it allows a firm to become as successful as it possibly can be.
Strategic planning is the process of defining where an organization wants to go and how best to get it to that destination. Both of these aspects of planning can help a firm. A firm needs to know what it is trying to do. For example, a store needs to know if it is trying to be a low-cost store that stocks many kinds of goods of average quality or if it is trying to be a store that distinguishes itself through the quality of its goods and services. A firm also needs to know how it plans to achieve its goals. A firm that knows this can follow its overall plan, confident that the plan is coherent. A firm with no plan might lurch from short-term decision to short-term decision without a clear strategy to guide those decisions.
Strategic planning, then, can help a firm have a clear picture of what its goals are and how to reach those goals. This is likely to make the firm more efficient and effective.