I also agree. I would aim for drinking 3 or 4 quarts of water - but that is not the same as carrying 3 or 4 quarts of water.
For one thing, if you arrive back at the spring on the switchbacks with a quart left, I would claim that you just carried 2 lbs of water to the summit and back unnecessarily.
Here's what I would plan to do. Carry 3 quarts up from Trail Camp. Drink 1 by the time you reach Trail Crest. Leave 1/2 quart in a canteen there, for the return. Drink 1 more between Trail Crest and the summit. The remaining 1/2 quart can be consumed on the way back, so you arrive at Trail Crest again empty. Now drink the 1/2 quart you stashed; you will be at the spring about half an hour later.
A few additional comments:
You can, of course, modify this plan however you want, by taking more or less water and drinking it at different stages. But the general logistics, I think, are sound. You can call it water rationing if you want, but I prefer to think of it as "drinking responsibly." (I see that in TV ads now and then.)
Second, there should still be a summit snow field; I can recall only one year in the last 52 that it melted entirely. You can get as much extra water as you want from the trickles, or add snow to your canteen to make more. (If you just put snow in an empty canteen, it will sit there in an icy clump for a long time. So make sure there is enough liquid water to have a slushy mixture.)
Finally, if you like to save on weight whenever you can like I do, err on the side of taking less. If you miscalculate and run out, being a little thirsty on the descent won't kill you.
