In article >,
sf > wrote:

> I roast vegetables a lot, in fact I roasted asparagus for dinner last
> night - but I never preheat my baking sheet and that needs to change!
>
> http://www.thekitchn.com/here-are-3-...at-your-baking
> -sheet-tips-from-the-kitchn-90504

If you roast them in a cast-iron pan, then preheating makes some sense.
If you use a thin metal sheet pan, then it doesn't make any difference,
because the pan can't hold enough heat to do anything useful.

Isaac