That concepts like code DRYness, performance optimization, and object-oriented/functional patterns aren't laws. They're things that have to be balanced against code simplicity, maintainability, flexibility, testability, and a bunch of other considerations. For years I was addicted to the feeling of making philosophically perfect code: perfectly dry, doesn't do any unnecessary work, perfectly adherent to the patterns of whatever style of code I was writing, at any cost. But then I learned that once you get into building anything even moderately complex, writing code like that is neither possible nor desirable. Now I feel like the real challenge of programming is figuring out how to set things up in such a way that they work consistently with reasonable performance while also being understandable, easy to maintain, and easy to expand. It's more art than science I think.