Well, you've read it before!
It's possible to have good results if happening to have fresh or perhaps very fresh product.
I don't know if it's actually the case but my wife says she was able to tell the difference, quite substantially she said, after about 10 days of having kept a freshly-made solution unrefrigerated.
Myself, I don't use T3 at a dose where I feel it anyway and so I can't say by feel.
I don't think UV is required for the degradation.