How you treat the dances that are likely to be your celeb's third and fourth worst depends on your expectations.
Pro-Nikita, Katya and Vito, who have realistic final aspirations will be wanting to get them out of the way now, while Zara and Eddie are still around to act as cannon fodder and keep a decent celeb doing a ropy routine off the bottom of the leaderboard. They'll save up their probable triumphs for Musicals Week and semi finals.
Karen and Graz OTOH are prioritising week to week survival, and it's probably only pressure from the producers that's making them do any ballroom (Eddie) or Latin (Zara) at all. The fact that that might land Eddie with the choice between foxtrot and VW in the semis is of purely theoretical interest at this stage.
Angela R is half way between the two, but I would assume that Kai and the producers don't have final aspirations for her and are prioritising keeping her in until Blackpool, dodging all the fast Latin in the meantime (I've changed my mind, she'll do Let's Face the Music and Dance for her American Smooth).