Many planners still consider "strategic" to be synonymous with "long-term". Executives enjoy long term strategic planning because it's usually pure fantasy. Consultants love to do long term planning exercises because they make everyone feel good. Yet long planning horizons are the root cause of visions and strategies that are too motherhood to be successfully executed. According to Peter Wright of The Planning Group "when we take executive teams through an exercise to create a 2-3 year practical vision, they are visibly uneasy. If they commit to a vision of the company only 8-12 quarters away, real plans will need to be underway within a few months just to be on track."
This sense of urgency is the best reason to keep planning horizons short. Bridging the gap between strategy and execution is difficult, and a vision that is both practical and compelling is the best foundation. A vision should drive the articulation of an organization's most crucial priorities, its "strategic imperatives", as well as a solid plan for how to achieve those priorities. Without that short, practical vision, turning strategy into action is almost impossible.
There is one important caveat: strategic planning, in particular vision statements should never have a horizon that is too short. A vision for an organization that is only 12 months away, for example, is likely unrealistic, and can cause a sense of hopelessness. This can be just as damaging to successful execution as a vision that is too long.
There is a place for a very high level, longer term strategic vision for your firm, but don't let it be a substitute for a practical vision and strategy that will be the drivers of real action. Keep your business planning horizon between 2-3 years to create plans that are practical, compelling, and stand a fighting chance of execution.