I stir nothing, but I use a 2-vessel BIAB setup. I let the mash sit unmolested for an hour and then pour heated sparge water over it to rinse. As stated above, I stir very well at dough-in and then try to circulate the grains as I rinse them, to varying degrees of effectiveness. As long as you have the doughballs broken up with your initial stir, you shouldn't need to stir again. Although, if you are having to reapply heat, you may be forced to stir to break up hotspots.