Ancient gas oven here that I’m not convinced has anything but one temperature. Everything takes twice as long to cook as it says on the packet but also burns around the edges before it cooks in the middle.
I don’t really use the oven much so 200 is fine for the few things i do make, and taking it out earlier for pizza or later for jacket potatoes means nothing ever burns. The only exception is when I made some polymer clay stuff and I used precise temperatures and would have done a heston if I had a thermometer
We don’t have gas lines here, so the oven is gassed from a bottle in the backyard and I’m convinced that our temperature dial is affected by low pressure in the bottle (feels like Good Science to me).
So I’m a full Heston wanker with an oven thermometer.