John Bush writes that he hopes no one objects if he raids the Gestalt corral from time to time. He hopes no one will demand that he go whole hog and become a Gestalt therapist, and he pays a compliment, saying he's a hard-nosed Behaviorist who finds something attractive in Gestalt therapy.
John - I'm okay and you're okay :-).
However, I'd like to offer a different metaphor. Let's say you take your friend driving, and he likes it because he's from Brian's outback and has never been in a car before. So, he watches you and thinks to himself, "There's not too much to this. When there's a red light, John steps on that peddle; he calls it the brake. When there's a green light, John steps on that peddle, and he calls it the gas. What fun!" One day, your friend decides to take the buggy for a ride all on his own. Once out on the road, he finds it rather thrilling. Being a creative sort, he even takes some initiative. He decides that if he comes to a green light he'll step on the brake, and if he comes to a red light he'll step on the gas - just to see what happens. Now, an experienced therapist would undoubtedly fall back on his or her own theory and "gut" if something went wrong at one of the intersections of process, and thereby avoid doing damage to the client. But what a way to drive!
Another analogy would be of a carpenter trying to drive a nail with a plumbline. I'm not as confident that even an experienced therapist would utilize the tools to their best design without understanding the way they fit in Gestalt theory. When people say they've been doing Gestalt with their clients, they sometimes mean they tried some empty chair work, or they pointed to a jerking leg and told their client to give it a voice (or something similar). People may try using techniques associated with Gestalt therapy, and obviously something will happen. They'll tell themselves they either liked what happened, so they might use it again, or they didn't like it, in which case they'll say they tried Gestalt and it didn't work. I'd contend that they have not really tried Gestalt therapy; they may have beat the hell out of some nail, but they haven't tried Gestalt therapy.
The practice of Gestalt therapy really depends on an understanding of the theory, coupled with some expertise in application, which is accomplished through supervised training. The model of training is workshop-mentoring (in most cases, although in Europe it's much more part of the academic system). People usually spend at least three years in training before they become certified, and in the United States, that's granted through the Gestalt institute at which they trained. Often, these are post-doctorate in the sequence of a person's overall preparation.
Anyway, John. No, you don't have to become a Gestalt therapist, but you might want to invest in some good training so that you understand more of what you're doing when you take the buggy out for another ride.