This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
It's not copied into each constructor. It's called once per instantiation as you noted. In particular, it is called between calling the superclass's constructor and resuming your constructor. Since only one superclass constructor is called, there is only one place between that and your class.