If you need to get going quickly to ride the wave of a fad before it fizzles, then fast, bare_bones planning may be all you've got time to execute. This works best when you've already got the infrastructure in place, perhaps from previous projects or an established business, and you can simply shift energy and resources to the new idea.
Who should prepare the plan? _ As a business consultant, this may sound like heresy, but I believe that any plan should be produced by the senior management of the organisation. That is not to say that the consultant does not have a role to play in its preparation. He does. Senior management should prepare the plan as they will then be able to present and discuss it, demonstrating to their audience that they fully understand their business and market. I believe that the consultant's role is to help facilitate the preparation of the plan, the consultant can help undertake the necessary research, and can cast a critical and impartial eye over the plan.