When working on training, the first commands you teach are sit and down. Trying to proof these behaviors by getting them to sit - down - sit - etc. the dog often catches on quickly and starts to automatically sit - down without the command. By teaching the command stand now you have a third command to bring in the mix without your dog being able to guess what command you are going to give.
Stand is an easy command to teach by just simply luring the dog to stand by walking away with the treat or throw a treat on the floor and the dog is sure to stand. The more you work on training the more your dog will be willing to listen to you.