Training your small dog to stay within boundaries is important to keep him safe, especially if he's ever going to be off-leash. If you have property the country, for example, you are not going to fence off your entire yard but will need your small dog to stay on your property within boundaries to keep him safe. Such a little guy could get hurt outside of the safety of your property. You may also want your small dog to stay within boundaries if you would like to protect certain areas of your yard such as a garden you worked hard to create.
Training your dog to stay within boundaries keeps him away from things which could cause him harm and protect your property as well as properties surrounding yours. Keeping your dog within boundaries also reminds him of rules to follow and why they are important. Whether you are keeping your dog off of your bed or off of the couch or within the confinements of an unfenced yard with the freedom of not having a leash, teaching your small dog boundary training goes far beyond the basic rules of staying where he belongs.
Basic boundary training will start with showing your small dog where he can go versus keeping him out of where he's not supposed to be. Giving your small dog boundaries allows him to have freedoms within the safe confinement you created. Teaching your small dog basic boundary training will take time patience and lots of repetition. Practice this training as often as you can at least once a day, if not more. You will show your small dog his boundaries and test his limits during this training. Be prepared to use an invisible line and potentially create a visible line your dog can use while he's learning to stay within his boundaries. Keep your boundary training sessions short and simple but repetitive and rewarding.
If you can schedule specific boundary training with your small dog it's a good idea because it will hold you both to sticking to a schedule and ensure the training is done on a regular basis. You may need to be prepared with yard flags or something to create a visible boundary line. Your small dog will also expect some high-value treats to learn boundary training. This will entice him to stay within boundaries and reward for a job well done during training. Boundary training typically takes several weeks, so be patient and consistent with your little guy. Show tolerance for mistakes and pushing boundaries.