Multitasking and Efficiency
Since the brain cannot fully focus on one thing when multitasking, people take longer to complete tasks and are predisposed to error. When presented with much information, the brain is forced to pause and refocus continuously as one switches between tasks.
In other words, this degrades human efficiency.
It is possible to experimentally prove that a person who is interrupted takes 50 percent longer time to accomplish a task. Not only that, he or she makes up to 50 percent more errors.
Multitasking with unified goals
Multitasking with unified goals can help to improve the individuals’ efficiency to great extend. To cite an example consider that you attending a seminar. You are carefully listening to the speech of the scholar as well as you are watching the presentation. The presentation slides and speech delivery both are on the same topic of discussion. The goal of listening speech and watching the presentation audio/videos/slides are unified. This will help you to understand the topic of discussion more effectively.