What a brilliant feature, which was lying right in front of me for months, but I did not notice it. In Power Query Preview dialog, every field name has a hyperlink. NOTICE THAT. Click on a column name to bring that column into view.
Now you never need to struggle with horizontal scrolling in complex data sets.
This is a GIF animation. Some colors are smudged due to GIF limitations.
Have you noticed the hyperlinks which appear in formula syntax tooltip in Excel?
Find out what that does and you will be amazed. Read this article for details.