The boss stage originally lasts for 3 hours, however mc, the madman that he is, decided to not leave after 3 hours ended, but continue enduring this trial. In the end, he was even shown nightmares that he dreamt of when he was but a child that he barely even remembered, after which, there just wasn't anything "painful" left to remind him of, thus the "completely conquered" part. Oh, and BTW, that all lasted for 3 DAYS, way past the original 3 hours. And this is why he got much better rewards, and so much attention from the gods.