If using white on shower tray, would this not look odd where it meets the internal if using colour, and would the 2 colours not smudge? I tend use the same coulour as the grout.
Tap up your runs before sealing. But if i have two or more shades of sealant I'd do all the sanitaryware etc one day and the following day do the other colour when the first sealant has cured to avoid smudges and mixing.