ProdPod, a Productivity Podcast

So, what are you doing when you're multi-tasking? You're actually quickly changing focus back and forth between each task. And just like a car, you cannot turn the vehicle in two directions concurrently. And every time you turn the vehicle, you must slow down, recalibrate the car's direction then return acceleration to your original cruising speed. This takes careful focus and time not only with a car but with a change in each task.
In essence "single-tasking" to complete a task fully as the only item you're focusing and/or working on is more efficient than the notion of multi-tasking. The ancillary benefits are focus, less stress and faster project completion. This all equates to more time to relax or accomplish more goals that are fulfilling to your productive life.