I've lightly dabbled into subpixel art, sorta.
In my experiments, each full pixel still takes 3 subpixels, but..
If you drop a white pixel at X coordinate, it renders 0xFFFFFF on the RGB subpixels.
But drop a white pixel on X+0.33, it renders on GBR.
Drop a white pixel on X+0.67, it renders on BRG.
All three are valid white full pixels, just offset by thirds.
I guess that would more appropriately be considered 'fractional pixels' or something though. Still neat that if used properly and creatively, it can yield higher resolution graphics, of sorts...