I have once or twice embarked on what I was sure was a well-thought-out, solid refactoring job, only to find that after a long process of cleaning, pulling out

I have once or twice embarked on what I was sure was a well-thought-out, solid refactoring job, only to find that after a long process of cleaning, pulling out common code, and adding the special-case logic, I had refactored myself in a giant circle. Every step of the process seemed like a local improvement, and yet I ended up where I started. It was like the programming equivalent of the Escher staircase: https://i.ytimg.com/vi/UCtTbdWdyOs/hqdefault.jpg https://i.ytimg.com/vi/UCtTbdWdyOs/hqdefault.jpg.