Is it safe to put a plate directly on a recently-on gas burner?
I don't recommend it. I have had a plate crack before after being placed on a recently turned-off burner, and on another occasion ended up with burned fingertips when I totally forget that I had done so. I have in the past used a cooling rack over recently used burners that gives you a bit of elevation, and an automatic work space/storage space. Hope this helps.