Should cake mix be used right after it's mixed ?
While I have not tried this personally, I suspect for best results you should use it right after it's mixed. In the past when I made banana bread (admittedly NOT the same as a cake mix) and I only had 1 loaf pan, the 2nd batch would go into the fridge for a couple of hours so I could bake, cool, wash and reuse the pan. That second loaf never seemed to rise as well as the first one. It still tasted great, just was not as tall. Nowadays I have multiple loaf pans. Anyway, my 2 cents. Happy baking. :)
I suspect you've already figured out the answer to your question is yes, the cake should be baked (not refrigerated) right after it is mixed. I have no experience with refrigerating any cake batter (rather than baking it immediately) so I can't report on what might happen, but I suspect you'd be unhappy with your results.