When using a conventional oven, you typically don't need to leave the oven door open before putting something inside. Unlike a microwave, leaving the oven door open doesn't serve the purpose of allowing the oven to cool down.
Instead, it's essential to preheat the oven to the desired temperature before placing your food inside. Preheating ensures that the oven reaches the correct temperature for even cooking. Most recipes will specify the required preheating time and temperature.
Once the oven has reached the desired temperature, you can place your food inside and close the oven door promptly. This will maintain the consistent heat necessary for proper cooking without risking burning your food. Remember to use oven mitts or heat-resistant gloves when handling hot oven racks or pans.