even more than that - it's quite possible the one who did it too fast have just recalled most of it from his memory, but the other is likely to have found solution for himself from scratch, which is usually much more valuable. Even the perseverance to find the solution is something worthy by itself...
(obviously, "mileage may vary", but still)
I had a friend in high school who proudly proclaimed that he never memorized trigonometry formulas, he would just derive them from scratch when he needed them. He would often run out of time on our regular 20-minutes long tests. Admirable but not practical.
