I've seen where some batch sparge brewers will stir their mash one or more times during the 60 - 90 minutes mash, to keep the temperature uniform in their picnic cooler mashtun. Due to temperature loss from opening up and stirring, they have to compensate by adding enough boiling water to get back to the desired mash temperature. I'm just wondering how many of you do this, or just live with the inevitable range of temperatures inside the mashtun due to hot and cold spots.
I've always just hit my desired mash-in temp, closed the rectangular cooler lid, and left it alone until the mash is over. As I brew outside, if it is cold outside I throw a couple blankets over the cooler to prevent additional heat loss.
I believe that I receive the general desired effects from the mash temp I've selected, but I have nothing to compare this to. My range of temps at the end of the mash due to hot and cool pockets inside the mashtun varies, but can vary by as much as about 3.5 degrees, but normally just 2 to 3 degrees.