Logic isn't always truth, but ultimately it doesn't likely matter. :]It doesn't make a huge difference, but it can help. I don't know the science behind it first-hand, but the recommendation came from my farmer/ag-biology teacher sister and my ag-science-guru niece, so I trust it. Their over-simplified explanation is that corn is difficult to digest for many creatures, including humans. Adding it at night when the birds are less active revs their metabolism while they sleep.
It made sense to me, my birds love the treat and it fills some of the gap left by fewer fresh greens. No matter how it all falls out, they generally "winter" really well, so there's no harm in trusting "farmers' logic."
I always mean to ask what's your kitty's name?