The last take-home test I did was for EE364a: Convex Optimization. It was a 24 hour test, and I had a cold. I booked a hotel room as my apartment didn't have air conditioning. It was brutal. I got most of the programming questions correct, but only a few of the proofs. The average of the class on this test (and most every other assignment) was 80%+. I got an A- overall in that class.

Perhaps this class isn't too hard for Stanford students, but I have to wonder about cheating when the averages on nearly every single assignment is that high. One clue was office-hours: Whenever I dropped by office hours, there was always a line (didn't matter the class). I quickly learned that TAs would often drop a hint that would make particularly hard problems easy to complete. It provided an unfair advantage to students who could attend office hours.

It also reminds me of the huge scam of cheating on the USMLE amongst Nepali medical students: https://www.medpagetoday.com/special-reports/features/113627

I've met many wonderful international medical graduates. Many have shockingly high USMLE scores. It is true that there's no time limit on their preparation (U.S. students have under 2 years to prepare during medical school, international students may wait years after graduation before taking the exam). Before that scandal, I never would've thought someone could cheat on the USMLE. Prometric test centers are crazy locked-down. But that's not how they did it. They did the long-game. Prior test takers would remember a handful of questions and just add them to a secret database. After many years, that database contained nearly every question on the exam. Test takers would work extremely hard - memorizing every single question. The reward of a U.S. residency is life-changing, I get why cheating was(is?) so rampant.