1. ~20 hours of the nonstop quiz is hardcore! Was, is and will be.
2. Still absolutely worth doing for many reasons. The simple feeling of achievement is enough, it's hard to explain how satisfying the "I can do it! I made it!" feeling. Also, it's one of the safest ways to put your mind in altered state. After sleep deprivation and heavy randomized load for multiple hours, you can actually feel how different your brain works now. And, as someone already noticed in comments to the event, there are some works that suggest it helps with anxiousness. I can confirm - for me, it felt like break statement inside the infinite loop. Some thoughts that weren't pleasant but was hard to get rid of, just stopped dead in their tracks.
3. The increase of distance from usual 36-48 to 500 questions shifts perspective and priorities. Missed 5-10 questions become a much smaller problem. One of the funny side-effects - no WC lines ever, even though we had a ton of people there. During small tournaments, everyone tries to relieve themselves during short breaks, and here - well, whenever you need this you just go and return few questions later.
4. My effective distance is around ~250 questions right now. Next time I need to plan my break to have ~50 questions rest after 250 played. That should help increase team results. After that mind enters some kind of limbo state - you aren't sleeping, yet it's hard to get all information in the same place and comprehend question as a whole - words just scatter in your head. It's especially hard in "W?W?W?" because most of the questions are built around complex interactions between facts, not singular facts themselves. On the other hand - when you try to focus really hard in that state - your brain tries to utilize some unexpected resources, like visual parts - some of the questions actually became mini-dreams with the vivid visual component.
5. It's hilarious when you actually manage to find the answer in that state.
6. Many thanks to amazing people in my team for a great time! You're the best!