I would agree, but literally, the latest recipe I read came along with a recommendation stating the use of 18 gallons of water for (sorry) 7 kilos of grain and NOT performing a sparge.I assume you mean 2.5 quarts to per pound?
You could do this but I think you will be disappointed with your efficiency.
Lots of water and light beer color can make you miss your pH. I do no-sparge mashing, and I'm adding gypsum and/or phosphoric acid to get into the 5.2-5.4 range. Darker beers tend to naturally have a lower pH during the mash.This sounds like a normal no-sparge BIAB recipe.
15.4 pounds of grain with 85% efficiency and high (80%+) attenuation will give you 10 gallons of a 5%+ ABV beer.
If you're looking to try it, all I have to add is that you really need to watch your mash ph or you can get a weird off-taste.
Some people have reported that with full-volume BIAB on Biermuncher's Centennial Blonde, for example.
When I do those kinds of beers, I use a sparge and add mineral salts to keep the flavor profile I want with all that water.
I get exactly the opposite result from full volume mashes on light grain bills... thin body, and close to 100% attenuation with a very thin, dry mouthfeel.Google 'thin mashing' - generally achieves maltier beers, just the way I like them.