There is an observable law in regards to truck backing that can make your life considerably easier if you will take the time to understand and incorporate it’s principles into your knowledge base. This law has to do specifically with backing up a trailer.

I have observed this law many times over the years and needed a name to refer to it by when explaining it to students. I gave it the term “The Law of Increasing Trailer Offset”, or “The Offset Law” for short. It relates specifically to the behavior of your trailer while traveling in reverse.
If there is such a thing as a “secret” that experienced drivers know that beginners don’t, this is it.
It is my opinion based on my experience that having a solid understanding of this fundamental law really sets apart the experienced truck driver from the beginner. An experienced driver that is especially proficient in alley-dock backing has instinctively become aware of these principles even if they don’t have a conscious awareness of it. You simply cannot be good at backing into an alley-dock without using these principles to your advantage.
Currently this law is not being taught in truck driving schools.