I also just continue my regular, high quality layer mash. It is made from a high percentage of corn anyhow. Feeding addition corn would simply be providing more carbs without the protein, minerals, amino acids and vitamins, so I no, I make no effort to feed extra corn. It would likely whack out our egg laying production if it became a substantial portion of their diet. We've found that even dropping from a 17% protein Hubbard layer feed down to a no-brand 15% layer feed had an impact on production.
Our hens DO tend to step up their caloric intake by 10% during the winter, however. That's understandable. They must generate body heat for self warming.