“Be token efficient but do not sacrifice quality in any way” is the new caveman

Adding this to the prompt: “Be token efficient but do not sacrifice quality in any way” — has resulted in substantial token savings using Opus 5 and Fable 5.1, no matter the thinking level. I just wanted to share this tip as you might find it useful. I've seen no difference in quality. Instead, the model prioritizes ways to intelligently save tokens by, for instance, not recreating the wheel if it already has it.