If six months ago you had told me such things existed I would have been very skeptical. But since then I have come across two examples. Example 1: contact lenses. Forced during a trip to wear just one lens (leaving one eye without a lens), I realized my sight was much better than when I wore two. I had sharp vision both close and far away. And the unlensed eye got more oxygen than usual.
Example 2 I also discovered by accident. My bike lock no longer locks. It is hard to see this, so if I fake-lock my bike — which I got for free — it is still sufficiently protected. My bike lock is now much easier to use. No more worry about the key. No way it can become impossible to unlock, which has happened once in two months. (To any Tsinghua students reading this: Please don’t steal my bike.)