What you set white DOT size does not matter except if you go larger, you get more white ink. So it is only good for if %200 white is not enough for you.
For color DOT size if you go small or medium instead of mix, you get less ink however you can go up to %200 for ink limit and that May be enpugh on CMYK. What advantage comes from this, if you go smaller DOT size on CMYK you cab print more details.