Do you change the cooking time if are same things on 2 shelves?

It depends on the oven and the food. Some ovens have a fan that circulates the hot air, which helps to cook food evenly on multiple shelves. If your oven does not have a fan, you may need to adjust the cooking time or switch the shelves halfway through cooking.

In general, it is best to cook similar foods on the same shelf. This will help to ensure that they cook evenly. For example, you should cook cookies on the same shelf, rather than one shelf of cookies and one shelf of chicken.

If you are cooking different foods on different shelves, you may need to adjust the cooking time for each food. For example, chicken will take longer to cook than vegetables. You may need to cook the chicken for 30 minutes while the vegetables for 15 minutes.

It is important to test the food to make sure that it is cooked through before eating. You can use a meat thermometer to check the temperature of meat, or you can cut into the food to see if it is cooked.