Something strange I've noticed when using AI for longer projects

I've been using AI pretty heavily for real work lately, and something I've started noticing is how hard it is to keep outputs consistent over time. At the beginning it's usually great. You find a prompt that works, the results look solid, and it feels like you've finally figured out the right way to ask the model.

But after a few weeks something starts feeling slightly off. The outputs aren't necessarily bad, they just drift a bit. Sometimes the tone changes, sometimes the structure is different, sometimes the model suddenly focuses on parts of the prompt it ignored before. And then you start tweaking things again. Add a line, remove something, rephrase a sentence… and before you know it you're basically debugging the prompt again even though nothing obvious changed.

Maybe I'm overthinking it, but using AI in longer workflows feels less like finding the perfect prompt and more like constantly managing small shifts in behavior. Curious if other people building with AI have noticed the same thing.