Slack at all levels is necessary to make the organization work effectively and to grow. It is the lubricant of change. Good companies excel in the creative use of slack. And bad ones can only obsess about removing it. - Tom DeMarco
Thanks to Frank Patrick for pointing to this one from Tom DeMarco and his book, Slack: Getting Past Burnout, Busywork and the Myth of Total Efficiency.
It can't hurt to repeat this over and over again. Effective operations requires open spaces to handle variation and uncertainty. Even fairly "uniform" operations, such as assembly lines and factories need white space. Projects and knowledge work need even more.
It is a complete myth to believe that keeping everyone busy will result in success.