How much does the quality of food in top restaurants change when the chef is away? (This does not necessarily have to be the "head chef" since guys like Batali, Collichio, Boulud are hardly ever in their kitchens; but in such cases). For example, LB is open on Christmas. I assume it's a safe bet that Eric Rupert will probobly have the day off. Are diners better off eating at LB another day?