Lou Castle: <span style="color: #3333FF">The only guy I'd learn e-collar usage from</span>
is a board member right here. He's written more posts on more boards in the sanest manner than any other. <span style="color: #3333FF">His site</span>
I have never used an e-collar, but if I were to require it, I'd become a student of Lou's before I ever pushed a button.
That said, I do use a prong. I do fit it per leerburg's page. I do let a butthead dog lunge and self correct while walking, and it takes about a New York minute for them to realize doing so is dumb.
After that, it's simply control, as in if they forge too far it starts to tighten, they slow, and leash gets slack. That quick, that simple.
Compulsion and correction have their place, but not with a puppy.
I feel the same about e-collar usage on a pup. Praise will get you farther, faster.
A six month old is a pup. But I like my shoulder in it's socket, too,
so use a prong to help teach self control or correct for any inappropriate aggression.
Never correct for recall. Never correct for any command not thoroughly understood through marking and praise over and over, so you know it's disobedience rather than confusion.
Otherwise corrections are punishment, and break the bond and trust and that leads to failure, abandonment, and shelters are already full of failures, so please, just don't go there.
As for the "trainers" who want to tell you how to train your gsd, ask them how many they've trained. If the class is full of purse dogs, find another trainer.
My not so humble opinion...but then again is any opinion really humble?