We all have been taught to handle guns for years and seen thousands of gun fights. Unfortunately, our instructor has been Hollywood. It is easy to say that you know the movie or TV show is fake, but the reality is that you have seen people walking around with their finger on the trigger and subconsciously it is internalized. Without proper training and diligent practice, it is difficult for many to overcome this error. I often have experienced shooters in class that say they follow this rule, but the reality is far different. When watching them on the line, their finger wanders all over the place and they need to be reminded repeatedly to keep their finger off the trigger.
For me a proper indexed position is not just off the trigger or on the frame, but high touching the slide of the pistol. When looking at the gun from the opposite side you should not see your trigger finger through the trigger guard.