Productivity increases by 30% when dual monitor is used

According to the article of the New York Times, the dual monitor environment, in short, the display area doubled in the environment connecting two screens, the productivity seems to increase by 20% to 30% as a result.
The Virtues of a Second Screen - New York Times

For example, it seems that when you write a manuscript you want to display materials on one side while writing a draft on the other, or that you need to work like "While seeing something and referring" with that kind of feeling.
Moreover, it seems to be easy to compare the price of the original image and the processed image also in the case of image processing, and also to compare prices when shopping online. Is it the strongest if you combine this with a tab browser?

Simple story, it seems that it is based on the same principle that it is easy to work if the area of ​​the desk doubles.