It's important to be accurate!

Donnie: Uh, 7:12am, October 12th, 197...

It was never addressed properly and I blame time constraints. Luckily, the fandom remembers, the fandom will always remember. There's a wealth of SAINW Fanfiction out there. Every time a new fan watches 2003 and approaches that episode, the fandom collectively holds its breath. The AU fanfics continue. Heck, even I'm doing it (although mine isn't about Don, it's about Mike).

There was technically a rule that Donnie got all the angst. His double Mutation arc was originally meant for Michelangelo, but as per a clause he was supposed to be constantly goofy, always silly, the butt of the joke, almost never serious except for the Battle Nexus arc. So the angst went to Don.