[0] https://www.quora.com/Which-companies-have-really-hard-algor...
[1] https://www.quora.com/challenges
[2] http://www.businessinsider.com/heres-the-test-you-have-to-pa...
I'm not against this type of training, I'm very familiar with and have competed in ACM ICPC, TopCoder, etc, but what I've noticed is that there seems to be a divide in the type of devs that are merely brute forcing and solving as many questions as possible in order to create their own solutions bank vs the ones who take a more structured approach of learning problem solving paradigms and algorithms/data structures in a way that enforces why they're used in the situations they are and how those can be adapted and composed to solve larger problems.
If you want horror stories... I've worked with a dev that didn't understand the concept of passing by value vs by reference. This was a person being paid 6 figures and has been writing code for cloud infrastructure with a fundamental misunderstanding of the underlying memory model. I've also had devs that didn't even know that an abstract data type like a map could be implemented with either a hash table or self balancing search tree and therefore no idea of when you should/can/can't use one or the other. This type of thing wouldn't really bother me if I was talking to a front end dev, since I imagine most of what they do is solve design problems, but it's very worrying when these are people working on the lowest layer of a public cloud infrastructure...
I wonder what the history of their mobile app is, though? It feels like it's a hybrid app, and it feels like it's developed iOS-first, Android-as-afterthought, so it may be the ugly stepchild of the team that gets no attention. "Does it build on Android? Ship it!"
Also, if it is hybrid, it may be a JavaScript team -- and JavaScript still has that "top developers love to hate it" aura [1], so it may be that some of the least talented Quora developers populate the team? (Apologies to the Quora app team, but ... 10 seconds to delete a paragraph?)
The worst of the problems seem to be when I'm also using the SwiftKey keyboard, so they may not see them internally. Somewhere along the way they're doing something pathological, though, because SwiftKey works like lightning in other apps, and only in the Quora app can get bogged down and end up so slow that I have to disable it and use the standard keyboard just to type anything at all. There's also a bug where I sometimes can't hit enter after a link I've pasted, and again I have to switch to another keyboard.
SwiftKey may be reacting to notifications that the text has changed, for instance, and Quora is sending 200 change notifications, one for each character changed, and then SwiftKey is querying the entire source document again each time... Or some such. Don't know.
It's not just SwiftKey related issues, though. Whatever they were using for rich text editing has been broken in different creative ways every few months, where edits wouldn't take, or what you're actually seeing would vary from what gets posted, or you can't edit the link text, or you can't GET OUT of the link text, so all the new text you type ends up part of the link, or ... It's been broken in so many ways that I've lost count. A recent bug I encountered was when I was pulling the text down to get to the top of what I'd written, I scrolled it down once too often, and that triggered a "refresh" ("drag down from the top" to refresh) which lost all of my text. Sigh.
The Quora app is really in need of a solid team experienced in app development, robust data handling, and proper UI behaviors. If it has competitive programmers working on it, they're solving the wrong problems.
[1] I used to be guilty of this, but JavaScript got better, linters now help prevent the worst legacy JavaScript issues, I changed my opinion in large part, and I use TypeScript now anyway. :)