Re: How Long and In What Manner to Great Mastery?
Abundant Peace by John Stevens.
He talks about Ueshiba pretty much splitting from Takeda around 1922. Stevens goes on to say that by 1925, Ueshiba was "invincible as a martial artist".
Ueshiba trains with Takeda 1915-1922, but mostly in short periods of time. And between 1922 and 1925, it seems Ueshiba learned on his own. Solo training? Whatever it was, Ueshiba got better and better from the teachings of Takeda -- and Ueshiba didn't need Takeda there all the time to do it.