Fairly or unfairly, ever since Napoleon marched from exile on Elba to the battlefields of Waterloo in 100 days, all leaders have faced intense scrutiny of their early days in office. Witness the coverage this week of Barack Obama’s performance since arriving in the White House . By contrast, less attention is given to any leader’s last 100 days. Yet these final months often do more to shape a legacy than the first few.

The well-documented increase in chief executive turnover means many more business leaders will be considering their own last 100 days in 2009. The average tenure for a CEO runs between five and eight years, similar to a one or two-term presidency. Leslie Gaines-Ross observed in CEO Capital: “Presidents retire from office every four to eight years without catastrophe. As much as we may identify a president with his office, even [an Abraham Lincoln or Franklin D. Roosevelt] is not the United States. Much the same is true in the business world.”