I think one thing most of these families have in common is that they never developed a clear plan for disciplining their children early on. I've done some research on this matter and it is almost universal taught by all the experts, that after the child is a year old it is important to establish boundaries and let them know clearly know who is in charge. It is also important for both parents to be on the same page in regards to discipline.
I know that it's easy to second guess these parents on the show but it's a lot harder than it looks. Most people go into all this and fly by the seat of their pants. In years past we didn't have to do this because there was usually some extended family around to help guide young parents. Now we are more isolated from our families because we live in a more mobile society.
We now have the benefit of research and scores of books to help guide us. I think it's important to take advantage of these resources just like our ancestors took advantage of having extended families and communities to help them.
DRONES