I wouldn't be surprised. The objective of design patterns isn't just to have a list of structures in your head you can rattle off in coding interviews. It's to provide you (the coder) with a way to think about program structure and function. Think back to when you learned functional programming. You can say "oh. functional programming is about programming with functions," but that's different than the moment you understood at an intuitive level how to construct programs out of functions. And different from the time you were able to reason about the operation of programs that are constructed out of functions.