Final answer:
Yes, cake layers should be completely cooled before icing to prevent the icing from melting and to maintain the cake's structure.
Step-by-step explanation:
True, cake layers should be cooled completely before being iced. When a cake is fresh out of the oven, it is still very warm, and the icing can melt if applied too soon. Allowing the cake to cool ensures that the icing will stay intact and maintain the desired consistency and appearance.
Furthermore, icing a warm cake can lead to issues with the structural integrity of the cake itself, as the layers may become too soft and be unable to support the weight of the icing and additional layers.