That's a good question. My gut says there wouldn't be any significant loss in 24 hours.
We know that if you boil water/wort for an hour, you've essentially taken all of the oxygen out of solution. If you were to leave that open to the air, because of the law of equilibrium, oxygen will eventually get back into it. To what degree of saturation depends on temperature, time, surface area, and movement of the water itself. If you expose it to pure O2, the point of equilibrium is even higher.
I think if you keep your fermenter covered when applying O2, the blanket of O2 that forms on top will tend to saturate faster than if left open to air which contains 80% less O2. This is one reason the OP is trying to get some real controlled data from those with the ability to measure saturation in PPM.
Aeration at the Homebrewing level involves a lot of guesswork and variables.
It seems to me that if you are not using pure O2, but you make some kind of attempt to aerate whether it be with aquarium pumps, paint stirrers or shake, you're probably going to end up in a safe ballpark as you will be maxing out at under 10ppm. But if you are using pure O2, there's a real danger of going too far with it. Without the ability to measure the outcome of one's proccess, it could be all over the place, and how are you supposed to get repeatability without knowing this cruscial bit of information?