The Rule of Fifty - Embedded.com

The Rule of Fifty

Though we all have a gut-sense that working too many hours iscounterproductive, a very short paper by John Nevison called “OvertimeHours: The Rule of Fifty” at ProjectSolutions (where you need to register) cites data from fourstudies conducted over a half century to show how productivity eitherdrops, or at best maxes out, as overtime increases.

The studies' results vary quite a bit. One shows that at 50hours/week workers do about 37 hours work, dropping to just over 30once the workweek increases to 55. The “best,” if you can call it that,results were from a 1997 survey showed wielding the whip can haveever-increasing productive rewards, edging up to about 52 productivehours for a 70 hour week. But they all show a nearly-impenetrablebarrier of around 50 useful hours or less, regardless of overtime.

Unsurprisingly the data shows a sharp drop in results for thoseworking excessive OT for weeks on end, averaging around a 20% dropafter 12 weeks of servitude. That means, as the author concludes, theRule of Fifty is a best case estimate.

The 2005 Circadian Technologies Shiftware Practices survey showedthat productivity can decrease by as much as 25% for a 60 hourworkweek, which jibes pretty well with Nevison's data. Circadian'sresults also demonstrate that turnover is nearly three times higheramong workers putting in a lot of OT, and absenteeism is twice thenational average. I'm not sure what that result means, since it'sawfully hard for an absent worker to be putting in overtime.

Fred Brooks claims that the average software engineer devotes about55% of his week to project work. The rest goes to overhead activities,responding to HR, meetings about the health insurance plan, andsupporting other activities.

The GermanEmbassy's Washington  web site claims on its web  sitethat the nominal workweek in Germany is 37.5 hours because “Theoriginal reason for introducing this system was to combat rush-hourtraffic congestion, but among the more direct gains are an improvementin employee morale, greater productivity, significant decreases inabsenteeism, greater flexibility for women who juggle the demands ofwork, home and children, and the increased sense of individual dignitythat the employees get from having a greater say in organizing theirown time.”

The last phrase may be true but seems awfully hard to measure.However, their conclusions about morale, absenteeism and productivityseem parallel the survey results quoted above.

What's your take? When does overtime become counterproductive?

Jack G. Ganssle is a lecturer and consultant on embeddeddevelopment issues. He conducts seminars on embedded systems and helpscompanies with their embedded challenges. Contact him at . His website is .

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