I was always a firm believer in "the hotter, the better". Then I noticed that some of my fabrics weren't returning to their original colors after cooling off. I noticed this on a bright red fabric and after I ironed it, it was a dull darker red. I have now turned down the heat on my iron and if I have a really stubborn wrinkle or seam and spritzing it with Best Press or water isn't getting it out, I will turn up the heat just to do that part and then immediately turn it back down.
Also, with starching, sizing, Best Press, etc. it is recommended that you allow the spray to soak into the fibers before ironing. Sometimes it will still be on the surface and your iron can burn it.