Decisions that seem small at the time can have a big impact on stratetic position. One of the most fundamental principles of Sun Tzu's strategy is that we must adjust to changes in climate. We cannot fight the environment, we must adapt to it. Strategies that refuse to consider what is changing, are always doomed to fail.
A good example was Newt Gingrich's support of the liberal Republican Dede Scozzafava. It seem like a safe choice in a minor Congressional race in NY State, a way to win the support of the local Republican establishment. But the climate has changed. Conservatives outnumber Republicans. Conservatives put principles above party. As other leading conservatives leaders, most notably, Sarah Palin, rushed to support the independent conservative challenger, Hoffman, Gingrich finds himself on the wrong side of the forces of change.