I'm sure there's a debate to be had on when there were the most Doctors on Earth at once (outside of actual multi-Doctor stories) ignoring each other. Like, depending on the exact date the Beatles episode took place, that could've had the First, Seventh, Twelfth, and Fifteenth Doctors all within a hundred or so miles of each other. Probably the Curator, too. And at least two Captain Jacks.A retired Doctor is only radical if we ignore all the times the Doctor tried to go fishing, or visit the Eye of Orion, or fucked around in ancient Rome. Or became the Curator.