First of all, there is no such thing as multi-tasking. Instead, there is task switching. Your mind is not able to focus all of its attention on two things at once. What it can do instead is switch faster and faster between the two or more tasks. This is an important distinction because it means that if you are trying to do two things at once, your mind will constantly switch between the two and this means time wasted during the switch. If you choose, instead, to focus on just one thing at a time until that one task is done, you can save time and avoid the need to switch tasks. In fact, studies indicate that your IQ drops by 15 points when you are trying to task switch, because it reduces the brain power you can apply to any given task.