Going for a walk

Lately I've been reading about a walk being "the dog's time", and that they shouldn't have to walk in the heel position. When I walk Harley, I don't allow her in front of me, and keep her on a pretty short lead. I bought her a prong about a month ago, and we use it for walks. I use the method of a quick collar correction when she's off track.She's learning well, and sticks close w/out pulling. I read about it being "her time" and thought I'd cut her some slack. I held only the end of her 6 foot leash, and lo and behold, in about 10 seconds I had my 65lb. Bully pulling me down the street. Does training have to be "complete" before they can be "on their own time"? (And is a dog's training ever complete?) Is there a "correct" way to walk the dog? Thanks.