Qs about sparging

pardon the rambling, i typed this out at work over the course of like 5 interruptions.
i've got a couple of ag's under my belt, and i've been thinking about the sparging process. not batch vs fly, but more like the inclusion of mashout. firstly, i understand how a mashout works, but i don't understand why. i know you would mashout to stop your conversion, but i've also heard of people doing really long mashes for high gravity ales, or sometimes mashing overnight. if i had to guess, i would suppose this has to do with how much actual sugar you are extracting from the grains, or want to extract.

this leads me to a second Q, oversparging. is that really possible? i understand that anything is really possible when it comes to brewing, but i wonder if anyone has actually been affected by this. you know, real world results and all that stuff.

lastly, why mashout when batch sparging? it seems to me that batch sparging is purely rinsing the grains, and just grabbing all the residual sugars left in the grist. since batch sparging doesn't take nearly as long as fly, i wonder why "stopping the conversion" is really necessary.
-->quick tangent
if the mashout process is truly there to stop the conversion, is it completely necessary to heat the water up? why not dump in cold water? there is really only three adverse effects i can imagine from this. you could argue that you might "shock the enzymes," but the sugars should already be in suspension and there is no further chemical activity occuring. maybe warm water picks up the sugar better than cold? it sure seems to help me get the crap off of my pots and pans when i'm cleaning them anyways lol. maybe it flows better between the grains and you have less chance of a stuck sparge. i'm not sure, does anyone have an idea on this one? lastly, the most direct effect i can see from sparging with cold water is it taking longer to bring the wort up to a boil. that might be the main reason to do it, or at least the best so far in my inquisitive mind....
cliff notes? why do we do what we do? hah.

Stopping the conversion requires raising the temperature to de-nature the enzymes. Batch or fly. I batch sparge and use hotter water for the first sparge.

Chilling to stop it is counter-productive, because A. you'll have to heat the wort again, B. cold water doesn't do a good job of dissolving the sugars, C. beta amylase is active below 130F.

david_42 said:

Stopping the conversion requires raising the temperature to de-nature the enzymes. Batch or fly. I batch sparge and use hotter water for the first sparge.

Chilling to stop it is counter-productive, because A. you'll have to heat the wort again, B. cold water doesn't do a good job of dissolving the sugars, C. beta amylase is active below 130F.

Click to expand...

i can accept this as an acceptable response there are still many other q's to be answered (and thought of...)