"I wouldn't sweat the sparge amounts at all. If you want to use full volume your beer will turn out just fine. If you want to do a sparge then start with the full volume and pull out one or two gallons to sparge with later and your beer will also turn out just fine. btw; you do not need to sparge with hot water. Just pull out your sparge volume and set it aside and use it as is when it is time to sparge."
Sorry, but I disagree. Not attempting to come across as disrespectful, but mash out temps are at least 168 F. Pulling out 1 gallon when the mash temps are "hit", saving and then using to sparge just won't cut it.