In the continuing saga of "A day in the life of Aqua at work", I spent a non-trivial amount of time today "cleaning up" old dead code. Stuff that an AI agent helpfully added a few weeks ao "just in case" we needed some other new feature.
Well, we didn't need that feature, and leaving a bunch of code around that doesn't do anything has always been a bad idea. It's a worse idea when AI comes along and thinks it does something and wastes tokens realizing it doesn't. Oh, well, I'm not paying for those tokens.

Anyway, this hearkens back to a software engineering principle: Do The Simplest Thing That Could Possibly Work (DTSTTCPW).
However, I fear a riot if I deal an 8-letter acronym, so I'll go with a narrower application of the above. Don't write code for things you don't need yet... you may never need it, especially in the constantly shifting world of AI: "You Ain't Gonna Need It"
Your turn to define YAGNI.