What achievements were the most fulfilling for you? Chances are they are when you achieved something that you thought was impossible. Even very high achievement means little when it is requires no personal stretch.
The same is true for companies. The seminal moments in the history of a company are when they faced up to and achieved the unreasonable. The regular delivery of good, but predictable results generates little emotion and releases little energy.
Unreasonable objectives raise the standards in an organisation. And the “Pygmalion Principle” shows that when high standards are set, people perform better to live up to them.
Another factor working against reasonable goals is entropy. The law of entropy in physics states that in any natural process there exists an inherent tendency towards the dissipation of energy. There is an exact parallel in organisations. Any strategy that you lay out will get diluted as it percolates down the organisation and over time – it will never get amplified. The inertia of the company will dissipate the energy and focus you started out with, pulling back towards the status quo.
If your strategy aims well above what the organisation thinks is reasonable, there is a chance that, after the effects of entropy, there is sufficient energy to deliver the change required.