Do I need to adjust oven temperature and cooking times to bake more than one Christmas cake at a time?
How you bake batches of Christmas cakes depends upon what type of oven you have. Fan ovens and convection ovens have a fan which drives the hot air through the oven cavity and keeps the teperature of the oven fairly even throughout. Theoretically you should therefore be able to bake cakes on several shelves without having to adjust temperature or time. However you should check your oven handbook for specific advice, and as the baking time for a rich fruit cake is quite long it is always a good idea to rotate the cakes 180 degrees the cakes one or twice during the cooking time.
For a gas oven the temperature will vary more according to which shelf your cake is on. You should not need to change the oven temperature but it is a good idea to rotate the cakes and also swap the shelves during the cooking time, to make sure that the cakes bake evenly. The baking time may be slightly longer, but you should start checking at the time recommended in the recipe and check regularly after that.
Also remember that round cakes will bake slightly more evenly than square cakes. The corners of square cakes can cook more quickly so square cakes will need more regular rotating in the oven.