I have noticed that the 3rd year is a kind of watershed time for sticking with GBD or moving into punitive measures.
I think that the go-with-the-flow of not nursing on a schedule has set up AP moms who do GBD to think that all schedules are evil and that their children will be damaged by them and it is robbing the moms of a crucial tool for having a happy and healthy 3yo.
Ames and Ilg state that the way to solve the problems of parenting a 3yo is to send them to preschool, and it's pretty much the only solution they offer. They don't say why it works (because it does) It works because the children are given a set of exact activities with a definite beginning middle and end, with their entire day in a predictable routine where they always know what comes next, they are given ample gross motor opportunities, and they eat snacks in such a fashion that their blood sugar never gets too low to be able to function like they might at home. They don't beat children in preschool, and the kids behave. This can happen at home. It just takes realizing that parenting an older LE is different from parenting a baby. They have different needs and their growing minds thrive on order and absolute knowledge of their boundaries. When they have no concrete boundaries, they push to find them....hard, and if allowed to continue, can make everyone in the house miserable.