Do you guys preheat the cooler by adding hot water in it first, and then adding your brewing water/ grains? May sound like a stupid question but I believe some coolers function a little better this way if you "pre-heat" them.
Not a stupid question at all. I've tried preheating and not doing it, and don't find any difference. I only lose a degree or two at most during a mash. I just hit the right temp differential on my strike water and all is good.
Edit - I do add strike water first, then grain, if I misunderstood your question.