Here in the U.S. I urge every project manager to manage hours, not just dollars. The reason is that it has become a national secret of sacramental proportions that no one in America keeps good time records. Timekeeping is sloppy, deliberately inaccurate, or just plain not done at all.
There are two dire consequences of this. The most important from the standpoint of even a hard-nosed manager is that inaccurate timekeeping makes it impossible to ever know exactly how long it takes to build 100 Function Points of software. That means you'll never be able to accurately estimate the schedule and cost of future projects, you'll always be in the dark. You may be able to get away with it today but some day you'll wish you could divide the size of the software delivered by past projects by the hours of labor.
The other consequence is a dropoff in performance. This may seem counterintuitive but it's been proven true 100% of the time. Bad timekeeping invariably leads to overtime, because managers believe their staff can accomplish anything they're assigned by just working "harder". But the 40-hour week isn't just a tradition, it's the maximum that "knowledge workers" can work before their cognitive skills start to fail. After more than a couple of weeks of overtime, both productivity and quality slip and performance actually drops below baseline.
And of course there's a social cost to overwork. People spend less time with their families, resulting in strained marriages, poorly parented children, neglected exercise regimens, and a steady diet of convenience food. There are monetary costs as well. That convenience food is expensive, as are the additional cars and extra hours of child care that busy families need, as well as the gardeners and tax accountants.

































