Sumo, Yes like these fellows say you can use FFF for priming, FF can also work for priming, and probably F as well. The more you shoot, the more you will sense just how fast and consistent your time is from trigger pull to ignition of the main charge. FFFF is more consistent from shot to shot in speed of the ignition itself and ignition of the main charge. Is it required? No of course not. Somewhere along the way you might want to try it and see for yourself. I am not trying to stir things up and always think people should do what they feel works best for them and their situation. My experience is based on hands on usage and fair experimentation and think you should try all the roads open to you before you decide which one to take. Good luck!!!
Robby