I mean, what Nicole does that's so smart (and how she had three acts in the top 5 last year) is that she picks totally different artists. Like, the difference between an Abi Alton and a Jade Richards and a Tamera Foster is just as big as the differences between James and Rylan and Jahmene, and that's so, so smart of her as a judge. She doesn't split her votes, and she can appeal to a different significant audience with any of her given contestants. If you hated Rylan, you probably loved James. If you hated James, you probably loved Jahmene. She's just the savviest of the judges.
I think both Louis and Gary are making the mistake of "stacking" their categories with 5 weak acts and one that has actual potential, to try to gather all of the votes for that one (the way Simon ABSOFUCKINGLUTELY TOTALLY DID in 1D's year; FYD and Belle Amie and Diva Fever, are you kidding me??). But if people don't connect to that one act, it's really hard to pull for them. (See the struggle with Union J last year; they were genuinely a great act, but with a bad mentor's song choices and bad XF marketing with that fake-turned-real ugly rivalry between UJ and D3, it just was sour.)
IDK.