Whenever I use the oven to prepare frozen French fries, the instructions tell me to pre-heat the oven to X degrees, and then put the fully frozen French fries inside when it's ready.
But it's often a waste of time to stand around and wait for it to slowly get ready, so I tend to put them in before it's shown with the light indicator that it's at the right temperature. Also, I take out the French fries from the freezer at the same time as I start the oven, and spread them out on a thing, so they are ready to go into the oven. Maybe this make them thaw a little bit.
Since the times specified on the package never seem to be accurate at all, it doesn't seem like it matters. But maybe it does?
Why should I wait until the very last minute to take out the frozen French fries from the freezer, and put them into the oven only when it's fully reached the temperature specified on the package?
Is there something about doing it in my "impatient" way which fundamentally ruins the food? Or have they simply timed it "directly out of the freezer, immediately at this degree" at the French fries research lab?