C+ would require a lot more then a night or two. C+ is pretty much at the hasu level. You'd have to 5000 points, and with 100 points per game that is won, that's 40 games(you start with 1000), in two nights. That's assuming they didn't lose a single game. Ok so 40 games, at around an average of lets say 10 minutes, and an additional 5 minutes for finding a game. That's 10 hours at the bare minimal. Now lets factor in some variables in this equation. First of all, 20 games a night is pretty stressful. Like that's serious hard core training for a foreigner gamer (meaning non-korean). One could not last that long without suffering a loss. Second of all, depending on the time you did this, whether it be the start or middle or the end of that season, there are many B-A gamers that start out as D. B-A is pretty much a gosu player, and A koreans are near pro. Even if you started middle or late season, you'd still run into some top class gamers, because not every1 starts at the beginning of the season.
New paragraph for relief... Now I am gonna take some A+ gamers into consideration for this "equation." The best record on Iccup was 87-4 by Light[gm], which is pretty kick ***. Other A+ players are like 120-30, 300-100, and so on. a 40-0 C+ would be like an A+ gamer in the making right there, and A+ takes a lot of practice (we're talking south korean coach training).
Now I can assume you guys didn't go 5 hours straight a night with no breaks, especially on SC, just because of the sheer intensity of the game. Also I am gonna assume he lost at least 40% of his games. 60% is a really good percentage to have. Realistically, I would guess it would take one of your friends at least 4 days 2 get C+. And that's 4 full days, not nights. I didn't factor in MOTW, i am sorry about that, but i am just going on averages and ****.
And that is the reason for my skeptical ism.