The world’s greatest fictional detective is someone who knows the value of concentration, of “throwing his brain out of action,” as Dr. Watson puts it. He is the quintessential unitasker in a multitasking world.
Multitasking is a persistent myth. What we really do is shift our attention rapidly from task to task. Two bad things happen as a result. We don’t devote as much attention to any one thing, and we sacrifice the quality of our attention.