There were far less stand up gun fights than one would think. But when one happened word got out. The "fast draw" came from the days of Wild Bill Hickock who wasn't really a fast draw artist, but fairly quick out of the holster, calm under fire, and an accurate shooter. In what I've read, he always held the gun up at eye level in a gunfight.
But people talked about fast draws, and I'm sure people just worked out ways to be faster whether they needed it or not. Kind like a guy buying a motorcycle that can do 200mph but lives in a large city.
There are some who became quite proficient at fast draw and shooting from the hip. Some amazingly so. But I think for the most part the fast draw artists of the 19th century were more wannabes than anything else.
