I said the exact same thing. And with an 85% 'white' rice, agreed. I could not get it washed that fast either. But with the 60% it was basically spotless. Almost no dust at all and the water ran clear after two rinses.
Again, I said and asked the same thing about the length we typically soak, drain and rest. The answer was 'polish'. That is what seems to make the difference. With this soak, water uptake clearly was fast. I think the key is that it could have absorbed more (being more porous if you will, being down to the kernel), but if it had, after it had rested and drained, it would have absorbed too much water.
That said, thinking and writing this now days later, basically we can get away with, and even need these longer soaks because the 85% polish inhibits water uptake so much compared to 60%.
Something interesting, is that with some sacrificial calrose soaked 1 hour, and drained 1/2 hour, it still didn't have that dry feel the 60% did after resting overnight. I wonder if it would ever get there, how much it is needed (it sure made steaming nice) and if a 24 hour rest or longer might be needed to achieve the same conditions.
Noob just surmising here, but it seems the goal of soaking is to absorb all the water you need to hydrate the entire grain, but in the out part (say 75%). The rest time is then to allow the limited water available to distribute evenly. With polished rice, it's easier to absorb more water than you need quickly, leaving a grain too hydrated. But with something of less polish, it may be near to impossible to over hydrate, and it's just waiting time to even out the levels.
Trying not to re-invent the wheel, some of this feels like other processes I've experimented with where procedures are taken and followed that work for one material (50-60% polish) and try to apply them to what is available (85%) without really knowing how the original procedure behaved.
That all said, I've tried the polished rice from SakeOne and don't recall it behaving this way...but that was my first batch and two years ago.
So, does anyone have some SakeOne/Steinbart rice around that can describe it's appearance post resting?