John Driscoll has pretty definitely demonstrated that every one - but one - technique in Ueshiba's aikido is contained within the Daito-ryu curriculum. (The one waza is aikido koshinage - for which John makes a very plausible case that it came from Yagyu Shingan-ryu) - http://www.aikiweb.com/forums/showthread.php?filter=John%20Driscoll&t=15096
In the 1920's, according to Takeshita Isamu's diary, Ueshiba reportedly was doing a lot of research on how to counter judo and "Kito-ryu" - (the exact meaning of what is meant by the latter is unknown, as far as the West is known - Kito-ryu as a school was already almost extinct - I've dealt with that a little in HIPS). From then, according to his students, Ueshiba was apparently "aikifiying" everything - as Sugino quotes him, "In aiki we do it this way."
So in short, if the accounts are correct, we have:
- Ueshiba doing martial arts - somewhat - and getting to be a really strong man
- Meets Takeda Sokaku - learns Takeda's jujutsu and probably some aiki
- Ayabe - r-e-a-l-l-y learns aiki and TRAINS - (remember, this is the guy practicing with his spear in the garden and stabbling so deeply in a cheery tree that they had to cut off the spear shaft and leave the spear head in the trunk of the three).
- Continued training with Takeda on an intermittent and increasingly fraught basis for another 15 or so years - AND studies countering judo.
- Increasing study of weapons - not enrolling in schools - auditing at best, and mostly observing - and "aikifying" it.
- Increasingly making (his) aiki(do) his own - combining all the while with his spiritual pursuits - so, by post war, his art was his own method, with an individualized way of training for power.
Oh yeah - Mark points out that it is impressive the "little" amount of time it took for him to improve - not twenty years. Part of that is surely talent. But I think we should count in minutes of training, not years. And then, make it - minutes of REAL training.