Because one cellular telephone conversation can disrupt the concentration of 30 engineers hours-deep into complicated debugging jobs, especially when it's one s

Because one cellular telephone conversation can disrupt the concentration of 30 engineers hours-deep into complicated debugging jobs, especially when it's one side of a lengthy dramatic argument. It takes each engineer about 15 minutes to recover concentration, in my estimation. So that's about 7.5 hours lost, or about a programmer day. Concentration is precious and fragile. If you can know just one thing about managing programmers, please know that.