Aston Merrygold had a bad week with one dance where I think Janette had made some duff choices on music and choreography. He found himself in the dance-off against AJ and Mollie, who was saved by Shirley using her casting vote, hence the fact that he went out. The difference is that Layton would very rarely be up against someone better, unless perhaps he has a week when he is getting 8s and is up against Ellie when she is on 9s and 10s.
However, I have vague memories of one series - probably in the early days - where one person who was a good dancer kept ending up in the dance-off. Eventually one (or more) of the judges said effectively that the person concerned clearly wasn't clicking with the great British public, and that they couldn't ignore that, and voted them out. Not sure that that would ever happen now.