The 3D's of dog training..distance, duration, distraction

I went to a trainer when my dog was a puppy. She discussed the 3D's of dog training during class. It goes like this. If your dog is learning something new you need to teach him the skills so he can complete the tasks 100% percent of the time whether he is in a new environment or around strangers or needing to follow direction for a period of time no matter what.
I practice the 3D's when I train a new skill or as a refresher to the old ones. If we are out on a walk or at a store or someplace distracting we will try to work a little because it helps with discipline and focused concentration. I also try to practice distance when we are in our yard or in the house. Sometimes I tell him to stay at the door while I get my coat and phone from the downstairs, or I have him stay in the kitchen when I go to the other room to do something. duration is something I typically will only use for long stays but, can be useful in other areas.
The idea is that while learning you should not expand on more than one area of focus at a time so if you are working distance keep duration at comfort level and distraction easy as well. The areas being expanded individually until each area is strong enough to have strong focus and control whatever the need. The way a dog brain works you need to set up for success so they gain confidence and don't get confused or unsure as to what they should do. They need to be clear about what you ask and focus on each individual area to help them learn.
The brain also makes it hard for them to remember when they are in a different setting. So many people will say " he does this great at home, and we get to class and he can't remember at all" Let any idea of impressing others or feeling embarrassed or ashamed of your dog. Trust that with time their brain will develop to the point they can do this or that at any place or time. For now they may not work well in class but, after a few weeks of focused distraction work in several settings and short sessions your dog will succeed and you will beam with pride.
My dog went to many classes when he was young, he would do great at home then at class all he wanted to do was play or sniff the other dogs. He had trouble knowing I was there even. I got amazing treats and he snubbed his nose, I brought sqeaker balls or tug toys and he couldn't care less. He wanted to play. Finally I decided it was ok. I would leave other commands aside and simply practice our focus. I would distract him and teach him leave it commands and work in very short distance and durations because he had little distraction control. I gave him super praise and would jump around with him making a fool of myself during class just trying desperately to keep him with me. I took a really reliable recall class and he did well except when a certain dog was around then he ran right over to her and we quit agility class because he would do one obstacle and then the same thing he runs over to the dogs. It was hard especially since he started off life loving all the other dogs and when he became of age and being he is unaltered he got in a couple little brawls and now doesn't like boxers. He likes most dogs and most of the time is great with male or female of most breeds but, certain ones I have to be careful with. I work these distractions in ways where I try to keep his focus on me. I have heard that if a dog goes through a trauma in formative times like the 9 month area then they hold those ideas strong in their decision part of the brain. We continue to work it.
Anyway the dogs minds do so much better with challenges faced singlely and when they acheive success it is time to regroup to another area until they are strong in all of the 3D's.
no matter what though make sure you always refresh on commands whenever you can.