At one point I developed a habit of converting any recursive algorithm I was writing into a loop instead, since I knew function calls have overhead and all recursion really does is lets you use the calling stack and flow control as an invisible data structure.

Then I got a question about parsing brackets properly during an interview and wrote a loop-based parser to solve it and the guy had to fish for a bit before I remembered recursion and realized that’s the answer he was looking for. My mind just wouldn’t consider using a whole calling stack when an integer would do the trick faster.