If there was a system that gave you whites you’d have to make the mark amounts much higher, 100 for a guaranteed white from a godlands dungeon, and 75 for a guaranteed white from a end game dungeon, of course the marks would have to come from a dungeon corresponding to the rarity of the item (75 shatters marks for an end game dungeon white, not 75 sprite marks for an end game dungeon white).
I think there should still be a random rotation, so you can’t just turn in sprite marks constantly in order to get sewers whites.