quote: "Do as few resizings as possible and preferably only the one to the final size."

Reducing size in steps is the only way to obtain a good result. You'll always lose information / image quality but less when the average that has to be calculated is 1/ not a simple division (like one out of two) and 2/ the number of pixels that has to be eliminated and replaced is as small as possible.
You have of course the right to disagree, but please give us a sound foundation. This is a non-tech user and I find your entry very confusing.
So please explain as your opinion goes against all mathematical logic.

There are no Borg. All resistance is fertile.