Technology has made it possible for us to do different things at the same time. Multitasking has become the norm, even expected, and it has changed the way we use mobile technology in particular. We not only expect our gadgets to do multiple things at the same time, we feel we are underachieving if we are happy doing just the one thing in front of us. While multitasking on mobile devices is nice, the fact is most of the time we'd be better off just focussing on the one task at hand.
The benefit of focussing on one job at a time has become clear to me since using various mobile devices in place of computers to do "real" work. While the tablets I use can multitask, the simple operation of displaying one app at a time turns the experience into that of computers of old, when only one program could run at a time.
Yes, I am dating myself but it wasn't that long ago when computers could only run one thing at a time. This dictated a usage pattern of starting a task and finishing it before moving on to the next thing. It sounds downright backwards, but to tell you the truth I believe most folks got more done this way. The single task, single screen operation forced us to concentrate on the one job before us, and that was a good thing in the long run.
Today it's a far different situation. We have multiple windows open on the computer, each vying for our attention on a continual basis. We are trying to work on a single task, but the other things keep shouting for us to look at them. This isn't a good way to work, but we all do it.
That's the primary reason I find using a tablet so productive. I start a task and find I almost always finish it in one sitting before moving on to something else. It only displays one app on the screen at a time, so my attention is firmly on the task at hand. It's effectively like going back in time to those dinosaur computers that couldn't handle multitasking, and it's honestly refreshing.