Bear with me on this dumb question. I have recently graduated to a Spirit-SP310 from many years of Q's or kettles. The issue is managing the burners for a small amount of high-heat food. It says to preheat the grill with all the burners on high to 550 or so. Got it. But if I only have one burner worth of food, do I then shut the other two off? Obvious answer would seem to be yes, but that's going to drop the interior grill temperature quite a bit when I need a third of it to be really hot. Is this the right way to do it? Thanks