Chiff - I believe Hector preheats his oven for that length of time so his baking stone can come to full temperature, thereby helping to regulate/maintain his oven temp. He find this especially helpful for baking breads.
That makes perfect sense. I didn’t factor in the preheating of the stone.
I have a gas on top, electric with convection inside range… I love it!!! However, I don’t like using the convection feature for baking. Items come out lopsided and two-tone (brown and white). Some of this can be avoided by turning and rotating the pans during baking, but I’ve never been fond of doing that. I save my convection feature for roasting (works wonderfully for that), so, unless you purchase a convection oven specifically designed for baking, don’t think you’ll be able to bake multiple trays of cookies at one time - I still find baking one tray at a time in the center of the oven gives the very best results.
LOL @ lopsided convection baking. I know what you mean. I didn’t rotate my pan once, and one cake looked suntanned while the other cake looked pale. (Luckily they were going to two different places.)
I worked in a bakery in southwest Colorado and the owners installed an old Bari pizza oven. I baked many things at once and rotating the pans was a MUST for even baking. I guess I got in the habit of rotating pans while working for them and now it’s usually second nature. (Except for the above referenced time - which convinced me I need to KEEP this habit…LOL.)
I like rotating cooky pans too because uneven baking affects them as much as any other baked product - and the texture of the batch can be very inconsistent.