I can't speak for RUSF, but shaft down is the way to go, though stand and turn works fine too.
During my adolescence, I became somewhat of an expert on rubbing one out on the toilet. Shared a room with my brother growing up (same bed for most of that time). Had a roommate in college. Shared a room a the frat house. Moved into an apartment senior year, but had a GF that moved in pretty much immediately. I might've been 22 or 23 before I truly had my own room for the first time in my life.
For the entire first half of my life, the horniest half, jerking off on the toilet was essentially my only option. Frankly, jerking off anywhere else seemed weird until somewhat recently.
Rarely do it anymore, but suffice it to say, I can understand the urge and/or necessity.
Also, I used to drive a lot for work and became quite proficient at doing it at 80MPH down the highway.