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.
Risk _ in our marketing plan we shouldn't only concern about making money or positive points, we also should address the risk we are taking. for example it is common for a marketing plan to capture things like, "require additional staff to handle sales call", "additional investment from the management budget will increase chances of increasing 10% sales target" and many more. Imagine if you can factor your risk earlier and think through it, wouldn't it be better for you?