My Villain Academia begins. How long will Shigaraki's training arc be, knowing he survives it by it being a flashback?

I feel like some things about this ark were changed from the manga, but I'll chime in once I'm sure.

But as a freebie trivia, apparently the mad doctor character had his name changed after his introduction (to the one the anime uses) because, for whatever reason, the author made his name a pretty obvious parody of a real life code name for war crimes committed by the Japanese army during WW2 including human experiments. You can imagine the backlash. More info if you're interested: Name controversy