Okay, I got your attention.
After a discussion with a friend, we ended up with this issue.
Being frugal, we want to make the most beer possible - within the recipe. The question is this:
A lot of people (those with 5 gal carboys, anyway) suffer from loss of potential beer with an active blowout
process. I just lost nearly a full gallon (another story for another time). IF, to avoid that, say a person did a strong, long boil and ended up with 4 gallons of wort. Then after 3-4 days when the blowout has subsided, COULD he add a gallon of water to the primary and end up with the beer the recipe intended?
Taken it to an extreme level of silliness one might end up with the soft-drink syrup process - which I know is just, ummm, silly. But to the extent above, would there be anything lost?