Re: Old O'Sensei video.
For decades now, the "must have" book on sportbike riding has been Keith Code's "A Twist of the Wrist".
One of the best take aways from that book is his discussion on how people approach improvement. Obviously the context is doing faster laps around a racetrack, but I would say it's equally at home in the martial arts (or just about any physical endeavor).
Code asserts that most racers try to go faster by *hoping* they go faster. They may think, "OK, I'm going to carry more speed through this turn..." but they don't know *what they actually did* to go around the turn before. They don't know exactly where they started braking, they don't know how fast they were going before they started braking, they don't know exactly where on the track they were when they got off the brakes, they don't know where they apexed or exactly how hard they got back on the gas. Since thy don't actually KNOW any of those things, the next lap around when they want to go through that corner faster, all they're left with is HOPE. They can't intentionally change any particular parameter to go faster, since they didn't know what they did before, and they don't really know what they're doing on this pass. So, really, it's just hope. They're trying to feel that they went faster. That simply isn't good enough.
Same thing holds true for budo. I think many of us do the exact same thing in our training (I did). We have a vague feeling of better or worse and we're just hoping to slowly drift towards better. But we don't really know what we did, and we're not actively engaged in changing anything. We're just hoping things get better...