When training a dog, a very common mistake is to go on and on and on in a training session until a dog checks out. This is very easy to do, especially when your dog is doing awesome! However, it's important to remember that dogs don't just learn through consequences, but also through associations and the habits they build. In addition, training in sets helps nervous or high-strung dogs stay calm enough to learn and gives them much-needed relief from the pressure of learning and thinking.
Here, I use short sets to work on making Pip's downs nicer and quicker. Note how short I keep the sets. Note the small breaks between sets to keep her from getting overstimulated (and for nervous dogs, from getting too overwhelmed).
With short sets, it's easy to keep the dog's motivation throughout that small moment. Thus, the dog associates training with focusing on you and trying her best. She'll build a habit of trying and working hard instead of walking away and ignoring you. With this method, you'll have a dog who begs for more training at the end of a session!