Toaster ovens often come with this instruction to "rotate past 10 (or some other number) then set time" to ensure even cooking and prevent potential issues with the oven's heating elements.
The reason behind this instruction is that toaster ovens use two heating elements, one at the top and one at the bottom. These elements are responsible for producing the heat required for cooking. When you turn on the toaster oven, both heating elements start to heat up simultaneously.
However, if you set the toaster oven to the desired temperature and cooking time without rotating the timer knob past a specific number (usually 10), only one of the heating elements may be active, leading to uneven cooking. The toaster oven needs to preheat fully before both elements work together to provide consistent heat throughout the oven cavity.
By rotating the timer knob past a certain point (e.g., 10), you ensure that both heating elements are active, allowing the oven to reach the desired temperature evenly. Once the oven is fully preheated, you can then set the cooking time for your food.
In essence, this step is a recommended preheating method to guarantee that the toaster oven is ready to cook your food evenly and effectively. It ensures that both heating elements are functioning and working together to provide a consistent cooking environment inside the oven.