Hang up the phone, turn off the TV and put away your kibosh. I was right earlier this month when I started musing on the concept of Return on Focus. The New York Times reports, among other factods, this:

In a recent study, a group of Microsoft workers took, on average, 15 minutes to return to serious mental tasks, like writing reports or computer code, after responding to incoming e-mail or instant messages.

Ennis thinks this particular statistic is directionally correct but numerically bogus. I can’t determine that one way or the other, but I do have to wonder how many years sooner Ennis might have completed his PhD without the distraction of email. It does illustrate how easy it is to get absolutely nothing done if you check email too frequently. But my interest in Return on Focus isn’t really about the microslicing of daily work, but rather in the lost time and energy in having too many “top” priorities, or having a corporate mission that tries to serve too many masters. Let’s read on…

…Computers can help people juggle workloads, according a paper presented this month at a conference at the National Bureau of Economic Research. The researchers scrutinized the work at an unnamed executive recruiting firm, including projects and 125,000 e-mail messages. They also examined the firm revenues, people’s compensation and the use of information technology by the recruiters.

The recruiters who were the heaviest users of e-mail and the firm’s specialized database were the most productive in completing projects. “You can use the technology to supplement your brain and keep track of more things,” said Erik Brynjolfsson of the Sloan School of Management at the Massachusetts Institute of Technology and a co-author of the paper, along with Sinan Aral of the Stern School of Business at New York University, and Marshall Van Alstyne of Boston University.

But the paper also found that “beyond an optimum, more multitasking is associated with declining project completion rates and revenue generation.”

For the executive recruiters, the optimum workload was four to six projects, taking two to five months each.

OK, so there’s the bit I was after. Let me quote it once more: “beyond an optimum, more multitasking is associated with declining project completion rates and revenue generation.” So recruiters get benefit from multitasking up to 4-6 jobs, but bayond that total productivity suffers. I like that the research actually brought it home to revenues.

The productivity lost by overtaxed multitaskers cannot be measured precisely, but it is probably a lot. Jonathan B. Spira, chief analyst at Basex, a business-research firm, estimates the cost of interruptions to the American economy at nearly $650 billion a year.

Yowza. I wonder what share of the $650 billion I could recoup if I stopped checking email? Or stopped blogging…?