What was the outcome? As much as 90% businesses started by entrepreneurs and small business went busted or failed within a year. I experienced one of the many busts few years ago (with my cafe business) because i don't really have a proper and "the few solid sheets" called a marketing plan.
Imagine if you can do all these and manage all these in a marketing plan? Systematic, organized, well thought, innovative and captured all your pertinent business information, don't you find having a marketing plan is useful for your business?