Not really. 9 times out of 10 a recipe will give a minute range. Like 9-10 or 17-19 minutes. Very rarely will a recipe say do exactly x minutes.

Preheating isn’t mandatory, hell it’s not even mandatory on an oven, it just provides best results and consistent results. If you put something in there that requires 15-18 minutes. You either can put it in cold and do around 17 or 18 minutes, or you can preheat for a minute or two and do 15 minutes.

They fact people are arguing that preheating doesn’t do anything is the stupidest fucking argument I’ve ever heard. It’s simple physics. And hot air is not going to make a metal tray with holes become hot instantly.