Meditation and multi-tasking

A meditation teacher once said that meditation helps to improve our focus and concentration. He illustrated a person's mind with a diagram with many short wiggly lines. These lines represent a person's thread of thought which exists at the same time or a short period of time (don't remember exactly). After a period of meditation practice, the number of lines decreases and the length of the lines increase. Ultimately, there is only one line left. Only a thread of thought at a period of time, which means total concentration.

Is that useful enough to warrant attention? Imagine running multiple background programs on a pc at a time. The program with focus will surely be slowed. That's why I like to get rid of unnecessary background processes which are eating up my CPU cycles.

As a side note, it seems to me that people speak highly of multi-tasking these days. I beg to differ. We only have one brain, so we are not really multi-tasking. We are split-tasking. We devote a small portion of attention for a small part of a task, and then switch to another task in the queue. Our minds make it seem like we are doing both at the same time. In fact, that's what a single processor system does as well.

But then, as a counter-example, many people seem to be able to study effectively while listening to music. Even better, many people listen to music almost all the time, regardless of whether they are doing something. I have tried, but I just can't concentrate on my studies while enjoying the music at the same time. Maybe I'm old fashioned, but I sure won't run an anti-virus scanner while I'm playing a pc game.