......exactly..my only question/statement is shouldn't "batch volume" be what you are left with after bottling/kegging? a 5 gallon batch means you are making 5 gallons of drinkable beer. yet, beersmith defines "batch volume" as what you put into the fermenter. so in order to change what goes into the fermenter, the entire recipe is changed.

Brewing to reach a specific gravity wort with a certain volume of wort is one of getting the concentration of sugars correct. A cup of espresso and cup of weak coffee might have the same amount of coffee grounds, but one is highly concentrated and one very diluted.

That's the objective on brew day: to finish with that exact concentration of sugars (SG) in the amount of wort needed to fill the fermentor to our desired level. Your EE% estimates the total sugars you'll rinse out, but it is the amount collected that determines the concentration (SG). Ever over-collected, and then boiled longer to re-concentrate the wort? That is a good illustration of 'batch volume' at work.

If we hit that 'concentration' target, then we get the beer we wanted, and whether it fills 48 or 51 bottles is determined on bottling day. For ex, what if you spilled half the bottling bucket on the floor and finished with 24 bottles? The OG and FG are unchanged, and you still have 24 bottles of wort/beer of the perfect concentration you aimed for. What gets packaged is largely independent of brew-day math, other than padding your batch volume to ensure you reach your packaging goal.

That is also why telling BeerSmith all your typical losses is vitally important. BeerSmith assumes everything that goes in will come out, so losses must be factored in to get the concentration correct. Underestimate trub losses, and the wort is weaker because it is diluted across more wort that BSmith did not know about (i.e., bottom of the keg), just like making espresso in too-large a cup.