Re the study tubers not trying again, Jack Edwards has (three times?) but he seems obsessed and has wagered all his self-esteem on getting in. Jade got hooked by the Minerva scam's claim to be more exclusive than Oxford, and the brain stopped thinking right there. She paid a deposit upfront before finding how much it costs per year (cleverly hidden by Minerva on their publicly available Costs page) and that Minerva didn't do the courses she talked about taking (cleverly hidden by Minerva on their publicly available page about their courses. As for Ruby, I agree with those who say a gap year would have done her the world of good, but she probably wouldn't have taken advantage of it, and a second rejection would have been catastrophic.
Not getting into Oxford was the best thing for Ruby and her mental health. She would never have coped with the 2 essays + other work a week, the short terms and quick topic change, and the tutorial system. You don't have time to endlessly rewrite essays. You don't have time to turn all your notes into flashcards and drill them. You don't have time to draft and memorize what you will say in your tutorial. Your tutor will be trying to have get you to spontaneously think through criticisms of your arguments, which is where Ruby fell down in the interview. She took a massive folder of stuff she memorized but struggled to think on her feet when given an unseen poem. She was also at the height (or should one say the lowest point?) of her first year Hermione idealization and had only just published Erimentha...so I can (with a lot of cringing) imagine her approaching the interview as Hermione/Erimentha. Let us hope she didn't at one point say "Did you know...?"
As for Jade, I am ashamed to say I liked her a lot back then in the Oxford application days, before she fell for the Minerva scam and began lying to her viewers. But I don't think she would have done well at Oxford either. She said months before that she left a better performing sixth form and rejoined her old "big fish in small pond" school because of the top school's reluctance to help her when she was struggling in maths (I think). The impression I had, especially after she got all A*, was that she preferred to be spoonfed the material and memorize it, rather than puzzle through herself. And like Ruby's reliance on memorization, I can see that attitude revealing itself in interview and being a real problem if she got in.
I have zero experience with Oxbridge as I'm not British but from what I've read here about the selection process and from my own experience as a somewhat capable uni student, I think the way Ruby approached the exam was completely wrong.
She spent two years preparing by obsessively reading, annotating and memorizing everything and anything she could get her hands on, only to freeze when she was asked to comment on a poem. I'm sure she knew going on that one of the things she could be asked to do was comment on a poem she'd never seen before. That's not really something you can prepare for. I mean, of course you need to be knowledgeable about literature and poetry, but other than that, it's more about what you are able to come up with on the spot than remembering something you read six months ago and repeating that.
What I would have done (again, I'm talking completely out of my ass here, just sharing what my approach would have been) is I would have tried to practice analysing things I haven't seen before. Maybe tried to establish a rough outline of "where to start" to avoid the panic moment where you don't know what to say and your brain is racing in a million different directions. I find it's very important to be able to anchor yourself to some core elements you can talk about or handle first that will naturally lead you forward.
As people who have studied classics will know when you want to translate a Latin or Greek text you find the main verb first, its subject, and you go from there. You don't frantically read the whole text and panic because it's all gibberish and you don't know where to start.
I think that's what happened to Ruby, she read the poem and reacted like a chicken who's lost its head, did not know where to start, couldn't form coherent thoughts, could not remember anything she'd read because of course, it's too much information and none of it is directly relevant to the task at hand, and her brain just shut down. Complete panic mode. And the rest is history, she failed and all of her hard work lead her nowhere, because it was not contextualized to what she'd be asked to do.