Fundamentals, Cycles & Trends (FC & T's): Your plan, if done in advance and thoroughly, should provide and excellent foundation from which to work. Even the best plan still has to react to outside forces that will influence your best intentions. Identifying certain fundamentals, cycles and trends that may impact your company is a prudent way to being able to develop a contingency "plan B" in the event an outside force rears its head. A series of key FC & T's should be monitored throughout the year so that if required, your plan can react. Certain FC & T's may include wholesale pricing, weather, commodity markets or labor market impacts that are out of your control. In my opinion, developing contingency plans in advance for these outside forces at least gives you a fighting chance to react favorably.
I mentioned the financial aspect of a plan earlier, so let me add this. Another fact about financials to consider: not all business activities are about making money. Point being, in most enterprises financial considerations are centric to the document. But there are some other considerations. For example, a few years ago I wrote a plan for a new subsidiary that was focused on developing an inventory of patents. The potential financial returns were years into the future. Those patents may or may not ever have commercial value. Another example is a non_profit enterprise that has need for a complete roadmap for growing their profile in a market, of which a marketing plan would be the centerpiece.