Wow, There are some misconceptions flying around on this thing
First off bitework on a beginning level, drive building, rag work, tug etc work is done right away with puppies or young dogs regardless of if they have any OB training or not, considering that the young dog or puppy is showing proper behaviors for their age. You do not need formal OB to start training bitework.
I can't tell you how many times a younger dog is brought to us that has completed x amount of OB titles etc and now they want to do bitework, that will not leave the handler for anything. It's counter productive to go all one way then come back to go the other. For all these people that are winning FR or SchH titles without prong collars, there are thousands of handlers that have clicked and treated their way to ob title after ob title, and their dog can't use the drive they have to do bitesports. There has to be a balance in there, and that is the trick.
That being said, downs, sits, learning the heel position, out, retrieve, etc are all taught away from the field and away from decoys. A dog must be very solid in those before expecting them to perform then when a decoy is present. I would never expect a dog that didn't have a very solid sit or down to perform that action on a training field, its not fair. But that does not mean that no bitework can be done without OB first. Learning grip behavior, using drive, developing power and drive, etc, can all be done in the abscence of OB in the beginning.
as the dog progresses OB is added to the bitework routine. In trials OB is a huge part of bitework, more so in Schutzhund than FR. SchH is more of a team effort between handler and dog than FR, that is a lot of the dog on its own, but that is a whole other topic. When this OB is added is when I would use a prong if I had to. Most of our young dogs get a prong collar at 8-9 months of age, but no leash is ever attached to it. Its' just to decondition them to the collar being there so if it is ever needed, its not something new to them.
anyway, 9 times out of 10 when you take that dog from ob away from the field and OB to the field with a decoy, and you want to heel, the second you start moving the dog will break its heel position and break for the handler. It happens almost every single time, and if it doesn't happen the first time, it will happen the second. Simple question, what happens at that moment? The dog will hit the end of the leash right? Do you think the dog learns something in that moment? I sure do. It doesn't take very long for a dog to learn that when it heels correctly, it gets released to bite, when it breaks on its own, there's a consquence that isn't very pleasant.
In a case that just happened last sunday a club member was dragged like a bucked bronco rider and crushed her wrist as well. Some dogs don't care what's holding them back, they're going to get that bite. Sometimes a prong is a necessary safety measure, for the handler and the helper (decoy)
Sometimes a prong is used for drive work. As a dog moves futher along the must switch between prey and defense drives. A prong is an absolutely wonderul tool for that exercise. Basically when the helper is making prey movements the the dog is being held by the flat collar, when the helper turns and makes frontal pressure, the prong is used, adding discomfort, that seemingly comes from the helper and will help switch between drives and intensify that drive. you may not see a need for it as a general dog owner, but that doesn't mean that the need doesn't exist.
My personal dog wears a prong collar when we train, I rarely have to use it, but I do. I miss points during our OB routine, it happens, i'm not perfect and neither is she, but one thing is consistent and that's the comments on our relationship. Whether it's from the judge, the interpreter, crowd members, or just playing in the park. Yes, using a prong can hurt your relationship, if you abuse it, same as giving your dog free access to everything will result in a dog that could care less if you are in its life or not, again,not what I would term a good relationship. That's why I always say there is balance. Dogs MUST learn consequence. Its' hardwired for them to do so. I can't tell you if turning your back on the dog is consequence enough or if a good yank on the prong collar is.
and I've seen a good number of very good bully breeds doing schH and FR. Granted GSD's and Mal's seem to rule, but bully's are great dogs. If they didn't have the rep that they do I would probably have some. the main reason I don't is "if" and accident were to happen and someone got bit, it would get blown up astronomically becaues #1 because of its rep, and #2 because it was bite trained. But that's my decision for me personally, I won't judge someone else's, because other than that they are very loyal, bidable, athletic, have great drive etc. Everything you need to be,IMO, a complete dog. The best GSD's aren't bred to be human aggressive either, nor are Mal's. The ones that are, aren't the finest specimen's of the breed and should not be doing this sport.
anyway there were other points I wanted to make, but I can't remember them right now, oh well.