The Lie of "medium-high" heat

I use medium high mostly just for searing before broiling. Also use it briefly for shrimp (less than a minute) before making a stir fry where I reduce to about a four after adding the other ingredients. Only because I like to reduce the overall time and temp usually called for in stir fry recipes that include shrimp. Can't have rubbery shrimp and call yourself a southern Louisianian.