“What separates person who gets 250 vs 270?”

Interesting perspective but way too broad. I wrote 25X while having done 3 qbanks including mehlman and most of his anki deck. NBMEs 270s. Test day execution, and ethics/QI (score report- in 3 of them I had english knowledge deficit) dropped my score. I strongly believe in these high scores what matters is test taking skills, test day, and, thirdly, luck. Then after all of these, the 270s may have the little tiny knowledge gap to remember that alkaptonuria causes ochronosis.