This might be an unpopular opinion, but maybe grinding leetcode for 2 months just made your friend a better programmer in general.
I’ve seen people on here say curious things like “I’ve been a software engineer for N years, but I wasn’t able to get past advent of code day 3”.
At a certain point you have to wonder if, no matter what they tell you, these people are just bad at programming.
That’s not to say they can’t improve, of course, nor is it saying leetcode is the best way to improve. I’ve never done leetcode myself, I can’t speak for it.
He said, the actual interview questions were easy after that.