I got to try out the myth of multi-tasking last Sunday and I can confirm that multi-tasking does not work.
Let me explain. I have a regular Sunday morning routine. I use Sunday mornings to do my admin, and to prepare Materials for the coming week. I know exactly how long it takes me to complete my Sunday morning routine tasks - it takes roughly 1 hour 20 minutes. This morning, my wife called me while I was in the middle of my Sunday routine, and asked me to find a file on her computer and email it to her. Foolishly, I decided to do both the file finding and editing of a document I was going to send to my clients at the same time. I ended up taking 2 hours to complete my usual routine tasks.
It did take a little while to find my wife's file, But not too long, maybe 10 to 15 minutes. But because I was trying to do two tasks at once, I didn't notice that it always took me about 5 to 10 minutes to get back into the zone I was in before. It was this that caused me to spend more time on my tasks that I needed to.
The thing about multitasking is that people think they can do it. And perhaps they can do a limited amount of multitasking. But, And this is a big but, it is not that you are doing two tasks at once that causes the delay, it is the fact that you are actually task switching which means that you need to spend on average 5 or 10 minutes refocusing on each task. This is highly inefficient.
What you need to do is to prioritise which task is more important than the other. What I should have done is stopped doing my routine tasks and focused 100% on finding the file for my wife. But the opportunity to do this experiment was too good to miss. The result really did surprise me, I expected to have an additional 10 minutes or so on my routine tasks, I was not expecting a 10 minute task to cause me to spend nearly 2 hours on some routine tasks that usually take about 90 minutes max.
So the moral of this story is never never never multitask. If you want to be more efficient, more productive and get more things done in less time then you need to focus on one task at a time. If necessary learn to explain to your co-workers that you need to finish the task you're working on at the moment before doing the task they want you to do. Alternatively completely stop doing the task you're working and start working on the new task with complete focus.
Focusing on one piece of work at a time will give you huge positive results in your productivity.