CR,
We have read that multiple "rinsings" are more thorough than a single rinse. Which plays out true when you are rinsing the bottles or carboys you just washed. It makes sense that the same principal would apply to batch sparging or "Rinsing the sugar out of the grains".
To us this gets down to the whole "Volume" equation. For new all grain brewers we'll restate the basic premises.
To achieve the desired Batch Volume, we need to determine a fixed amount of water for our entire process less the basic losses from Absorption, Evaporation, Cooling Shrinkage, and other losses that are dependant on our brewing system setup, like liquid trapped in the MLT, chiller, hopback etc and the amount you leave in the boiler to keep hot break, hops etc out of the fermentor. Once we know our system and can consistently produce that volume, each of us develops a process by which we apply that volume to the malted grains to make wort at the desired S.G. So we have to decide how much to use, and how to use it for the Mash. Then how much to use, and how to apply to the Sparge.
We said all that as much to keep our own head straight as anyone else. OK, we are familiar with a few basic concepts on how to apply the volume of water left after the mash for batch sparging. The first is that the temperature of the water should be as high as possible staying below 170*F. This is to keep the grist as fluid as possible allowing the sugars to dissolve into the water but not extract tannins from the husk. Usually the target is 168*F. This seems to be a common thread for all sparging schemes.
Now comes the part where we are unsure as conflicting thoughts that can be applied. The first is what I think CR implied. If I understand his thought correctly, many smaller rinses better than a single rinse. Since the total volume of sparge water is fixed, he keeps his sparge batches smaller so he can make "More Rinses". This makes sense as in getting soap out of bottles and carboys, we have always found at least three rinses were needed. A conflicting thought is that the sugar will dissolve more easily and more quickly in a larger batch of water than a small one. Based on saturation, a fixed volume of water can only hold a fixed amount of sugar, this amount is proportional to temperature. The higher the temperature, the more sugar per volume of water. Another conflicting thought is that sugar will be dissolved most efficiently the more fluid the grain bed is by both temperature and volume. The sugar is trapped in the grains or at leased much more difficult to dissolve when the grain bed remains dense and compact. These two conflicting thoughts imply that a single large volume of water will have the best chance to collect the maximum sugar by both saturation and accessability.
We don't know if we are correct, but we have resolved to always make make more than one batch sparge running and to maximise the volume of each. Making our typical house brews with 10 lbs of grain in a 5 gal Igloo MLT, We make two equal sized runnings with sufficient volume to "Float" the grains. We could make our preferred 3 rinsings, but are afraid that the smaller volumes would be more inefficient. Since we were making good beer to us, we haven't tried the three smaller batches. We should, we just haven't.
What have you guys found?