My understanding is that upon meeting Onisaburo Deguchi, he had found what he was looking for and kept to that path the rest of his life.
Regarding the "striving for something" of Ueshiba, I believe Ellis Amdur posted something about that element of his personality a while ago, but his views more or less jive with my impressions of the man.
As for finding what he was looking for with Deguchi, the general impression I get myself is that Ueshiba's time with Deguchi was in some ways quite similar to his time with Takeda Sokaku. That is to say he stumbled upon something that "spoke to him" at that point in his life, engaged in an extended period of intense focus and study on it, and then eventually distanced himself from it while still retaining a great deal of the core ideals. In the case of the Omoto-kyo, the distancing might have had some political elements to it as well (I think that is an oversimplification of a complex man), but if he was such a true believer and close student of Deguchi, why didn't he stick with it through the good times and the bad? Ueshiba seems to me to have been endlessly looking for something better, first from outside teachers, then eventually from the kami directly. In any case with both Daito-ryu and Omoto-kyo you could argue that he didn't really stick with them to the bitter end, even if the greater part of what he was doing himself came from them and he seems to have taken an idea from here, a concept from there throughout his entire life.
My comments about "winging it", while being a bit casual, I still stand by to a certain degree and are based on that pattern of "do something, move on" he seems to have had. This is especially true with elements of creating the organizational and educational models of the art, as well as the technical cirriculum itself, which is to say, he didn't seem to really have any plan at all (some might argue that Ueshiba's teaching model was based off of an older ideal on the method of instruction. While there is much to that argument, Ueshiba didn't really follow that method to the letter either). Technically he kind of followed Daito-ryu, but any ideas of formally organizing anything seemed to have been beyond him and mostly fell to his son later. Simpy put, he had people show up and train on whatever he felt like doing that day, when it gets too big, pass it off on someone else and let them deal with it, I can't be bothered as I have more important stuff to work on. Ueshiba never seemed to be working from any master plan and in many ways it seems to me like aikido as the art we know it now, was kind of a victim of his do it and move on tendencies. Not that he every stopped practicing and refining "his" art, but when he had finally gotten a decent level of name recognition for the art of aikido, he seems to have again "lost interest" as it were and dumped the whole thing off on his son to organize and he moves off to the country to do his own thing again. Many have commented that Aikido as we know it now is a product of the second Doshu and I would agree. When viewed very generally of Ueshiba's life seems to be him following whatever new adventure he discovered until he found something new and better. Martials arts... wait, a new life and adventure in Hokkaido.. Oh my god Daito-ryu..... wait..actually, Omoto-kyo!!..... hmmm, well maybe Aiki-budo... wait no, Aikido... come to think of it, aiki-farming in the country..... etc.
I think in many ways aikido is more a sum total of the various things Ueshiba happened to find himself stumbling into over the course of his life more than any particular gameplan he developed at some point. He was a rare combination of a man of great talent who was also in a situation to be able to freely pursue just about path that struck his fancy and he did so.
Also, if a guy today claimed to have gleened the proper use of the naginata by simply reading a comic book and then staying up all night that day thinking about it and getting enlightenment on the issue from the gods, regardless of how sincere he might be, we would say he was winging it (actually we'd probably say he was crazy), so I stand by my comments in that regard.
More random thoughts,