That (The Economist, 2016): "a growing body of academic evidence demonstrates just how serious the problem is. Gloria Mark of the University of California, Irvine, discovered that interruptions, even short ones, increase the total time required to complete a task by a significant amount. A succession of studies have shown that multitasking reduces the quality of work as well as dragging it out."
I have always believed that some situations need "less talk and more rock" (WBCN circa 1984) and the past couple of years I have felt guilty about feeling that way...this article makes me feel that I am still OK. :-)