I don't know about producing in one day what it would take another person 2 weeks to accomplish, but I do know there are some core features of my company's app that were created by a very talented developer that I don't think could be reproduced by some of our junior developers in a year.

I think it's a mistake to conceive of the difference as one between the tortoise and the hare, where the tortoise gets there, eventually. There are bits of this code that the tortoise just wouldn't ever end up producing if you gave them all the time in the world.