I am hardly a dog trainer. I was really proud when we taught our Great Dane to sit years ago. But as the handler of service dogs that go out in public, constant and continuous training is required to maintain sharpness in the dog, and to get the dog to fit your lifestyle. So we try and work some kind of obedience training/work into every single day.
We take these dogs everywhere with us, and most of the time, that means kids are around. The also means potential food being carried at dog height, food being dropped, toys, all kinds of fun things for a lab to grab. Perhaps your going out to a restaurant, and need to put your dog under the table. Is there stray french fries down there? Perhaps a half eaten churro at an amusement park? Or maybe something really dangerous to dogs like chocolate or grapes. Having a dog that knows "leave it" can make your life easier.