you can calibrate your oven though, like if you do want it to be accurate? so, to be just like the pros, put an oven thermometer in your oven and turn it on to say 300, wait until the burner shuts off (gas, listen to hiss stopping, electric listen to thermostat click off). loosen the small set screw on the oven knob, then set the knob temp to what the oven thermometer says, tighten set screw.
forget about the 300 dregrees... it doesn't matter.