When I ask entrepreneurs and small business owners, it is not unusual for not having any marketing plan. I once read that Sir Richard Branson never had any marketing plan when he started the 1st Virgin business many years ago. In fact in one study of entrepreneurship (I couldn't recall the name of the study) was that as much as 50% of entrepreneurs and business owners don't have a business plan and marketing plan when they first started the business.
But, before we continue, we must understand and accept that steps of the marketing plan are universal. It is a logical approach of the planning activity, no matter where we apply it. The differences you meet from a plan to another consist in the degree of formality accorded to each phase, depending on the size and nature of the organization involved. For example, a small and not diversified company would adopt less formal procedures, because the managers in these cases have more experience and functional knowledge than the subordinates, and they are able to achieve direct control upon most factors. On the other hand, in a company with diversified activity, it is less likely that top managers have functional information in a higher degree than the subordinate managers. Therefore, the planning process must be formulated to ensure a strict discipline for everyone involved in the decisional chain.