If you subsequently shove in another pizza and turn the oven back on again, it will not magically select the previously set temperature, but the maximum temperature of 250 degrees.
Adding 50 degrees to the heat when baking a pizza and not shortening the baking time will result in black smoke. Most smoke will stay inside the oven -- so by the time you smell it, it is already too late. Opening the oven will release the smoke, resulting in coughing and watery eyes. Also, the burned smell will linger for days.
Just so you know. Use this information to your advantage.
Don't ask me how I know this.