How important is it to stir the mash intermittantly? Provided you've thoroughly saturated all of the grain at dough-in what do you acomplish stirring other than losing heat?
I do a batch sparge and I don't stir until just before mash out. Last night I got my temperature under control, left the mash tun closed for an hour and ended up with 87% efficiency.
I stir every 20 minutes and fly sparge. I make sure to leave it alone for the last 20 minutes to set the grain bed. No problems here, 80% efficiency or better just about every time.
I used to stir, but I've stopped - I just didn't see any benefit. I leave the prove in the mash to keep an eye on the temp, then let it be until it's time to mash out.
I stir, but only because I mostly do direct-fired stepped mashes. So when you're applying flame to bottom of the kettle, it's important to stir to disseminate the heat. Otherwise...I do my big stir during sparge.