Obtain Feedback On Your Plan : When writing a business plan you sometimes end up locking yourself away. You might have unique ideas which lead you to seek some isolation and secrecy, or if you are going to be a sole trader you may only have one person to consult namely yourself. But it is fantastic to try and get broader input on your business plan - whether from a professional, or simply from friends and family whom you trust.
It seems to have been put there to fill the need to attribute a certain sum to marketing. Make sure you are researching each point of your budget, make sure that you are giving it context and it makes proper sense within your overall plan.
Drawing functional Plan: After positive result form the feasibility study, functional plans are drawn up. Some scholars and writers prefer to include feasibility study with functional plan but the two have been taken separately. Whereas only after the feasibility study can one go into the derails of drawing up functional plans which would determine the strategies for all the operational areas : marketing, Finance and production.
When I have received business plans, the very best responses come from people who have looked at the risks and have an answer for every question. What you never want is to throw a scenario at your plan and have to answer "I don't know what I would do in that situation". You want to plan for every possible contingency, and certainly all the major risks to the ongoing success of your business.