Concentrating on a single task at a time could be more rewarding than multitasking. Multitasking people might be doing harm than good to their productivity. Dr. David Meyer of the Uni­­ver­­sity of Michigan brought to bear that the time costs of shifting could be from the range of “25% to 50% time increment to complete a task compared to what would be involved if you were to only concentrate on that task” – CNN