Why would you worry about what's "typical"? Suppose you really, really wanted to do something incredibly challenging -- say, learn Portuguese, having never uttered or read a word of it in your life. Would you hedge your bets and ask around, wondering what the typical first-time Portuguese speaker is able to accomplish? Or would you in fact say, "Hell yes, I'm going to learn Portuguese as best as I can, because I'm motivated. It has its rules, and I'll learn those rules. And I'll practice and practice because it matters to me."
I am not being glib. There is no difference between GMAT success and success in any other challenging endeavor that requires practice. Oh, maybe one difference: Figuring out how to "think GMAT" is potentially easier than most tasks, because the GMAT is far more predictable. (Even more so than the Portuguese language.) The right answers are there. All you have to do is learn to pick them. The testmakers have calibrated their work to reward certain behaviors, and when you give yourself over to those behaviors, you will reap the rewards. What I'm saying is, the sky's the limit in terms of what any one individual can accomplish. Do it right, with the right attitude and grit, and you'll be happy with the result. Git 'er done. I am really looking forward to helping many, many more students achieve their not-so-impossible goal. I did it on Jeopardy and you can do it on your test. Mic drop.