This is an interesting picture and can be seen to illustrate the Adult being the executive of the personality.
The goal is for the Adult to be the one most influencing or controlling decisions in the personality with the Parent and Child having an influence. This is consistent with Freud’s view in psychoanalysis where the ego is meant to assume most influence compared to the superego and id. Indeed being a mediator between the superego and id.
I would draw a different diagram like this. It’s not the Adult in charge it is the Child in charge. Challenging the view that the Adult can ever be the true executive of the personality. To my mind -no.
The Child is the powerhouse of the personality. In the long run the Child ego state will always get what it wants. The main goal is to work with the direction the Child ego state wants to go. Of course the Adult and Parent can influence the direction somewhat where the Child goes. Some therapies focus on this. For example CBT very much focusses on increasing the Adult’s influence over the Child. It has developed many techniques with which to do this. Some religion based therapies may focus on increasing the Parent ego state influence over the Child’s direction.
However in my view the most powerful forms of psychotherapy will directly address the Child ego state wants and needs such that it wants to change its direction itself. Hence I have produced this diagram before. The main therapeutic goal is for the Child to want to change what it wants itself.
Most efforts are directed at the the executive of the personality, the Child, but still a significant amount of effort is directed at the Parent and Adult influencing the Child’s direction.