Yes what you say is similar to what I expected.
However, the exact person dealing with your case has complete discretion over what they do.
I experienced this when I was a D-2 visa holder to get my S-3 permit.
The law said I had to complete "a semester or 6 months of study".
After having completed one semester (but not 6 months), I went to the immigration office and the office denied my permit because 6 months had not passed yet.
Then I called my office and told them that the officer had denied my work permit.. But they told me: "no no, you can do it, you have studied 1 semester! Try again!". So I went back, had a different officer handling my case, and that other officer granted me the permit without any problem.
And the reason why I use the website is because the officers there used it several times to justify their decisions. So I think that if I just go there with selected printed pages of the website, it might work.. but I still have to test whether it works or not.
But anyway, thanks for the information. According to your friends, it's D-4 + 6 months = possibility to get S-3.
I guess I will try my luck at the Seoul immigration office later this year.
PS: if anyone has ideas or stories about this, please share!