What experienced Truck Drivers know that most beginners don't.
It's something beginning Truck drivers are expected to learn over time. I find they progress quicker when they are made aware of it early. I teach it to my new Class A CDL holders on day one. You can't be good at Angle Back, or Alley Dock backing without being familiar with it.
I did my CDL class last November. Dropped out of trucking at the time and felt really unconfident backing up at a 90, 45 or parallel. Later went to yard driving and in a matter of a few days had the understanding down of how my steering truly affecting my end of my trailer.
My gripe with the CDL class was that they spent a lot of time telling us WHEN to turn and HOW MUCH to turn at each point, making us STOP and turn at each point.
When I went to yard driving I was able to freely back and go at a faster speed to get a better understanding of how my turns were affecting the trailer tires, swing and pivot points. The ability to go faster and back into wide open spots was way better on my understanding rather than stopping and turning under command from a teacher.