Of course, we all do more than one thing at a time. For example, we can text and cross the road or text and drive a car. But the question is can we do two things with full attention at the same time. Probably not according to road statistics. Jumping from one task to another means that your attention is divided for a few moments and you lose your train of thought.
Doing one thing at a time is a good habit. Do everything you do with full attention. It can become a very helpful habit. Remember the old clock makers or today’s tennis players. It doesn’t matter what you are doing.It’s how much attention you give to what you are doing.
Try it next time you cook, drive, cross the road or brush your teeth. Maybe also next time you speak to a group or audience.