The mental part of maturity is much more complicated. I am sure that Luke never matured mentally until he was 8 years of age. He was in a constant state of pushing until about then when he became a different dog. Most of my dogs showed a marked difference in behavior at three years of age as far as guarding and protection of home and loved ones. Then again at the age of five they slip into that self assured, mature and wonderful age.
All dogs need an education. Dogs who never receive the required education; the ins and outs of living in a human world suffer mentally. They are never given the lessons on what is okay and not okay; making them seem like obnoxious adolescence long after age should have brought maturity with it.
Like us, our dogs are all different. I have been asked many, many times "how long until they are out of the puppy stage?" from desperate owners wanting to leave puppy-hood behind them. Some dogs are born mature; while others a lot more time to reach their full maturity. The more you offer your dog as far as rules, regulations, boundaries and guidance the easier they are to live with at any age.
Elsa is a very high energy girl; I doubt that will change much as she ages. Maturity is settling in and she is needing more reminders. Being a very confident female; she occasionally takes my requests and ponders on them. This means that I need to remind her every so often. If she is already busy doing something when I ask for a behavior; she may just flip me off. She is very good at ignoring when she feels in the ignoring mood. This has come with maturity. She is feeling very grown up now.
I do not want my dogs to be robots; but I do want them to listen and do as I say, when I say. It is important that our dogs comply. Patience is required from us when dealing with immature dogs. Much time should be spent on giving them an education. Using "he's just a puppy" can only be used for a short time; although many use it well into adult years. Using the excuse into adulthood becomes a lie we humans tend to convince ourselves of.
Elsa will turn 5 in a couple of weeks; she is quite the lady.