I think there are different definitions of "best". I was referring partially from a physics standpoint, where the metric is efficiency of energy (the least amount of force needed, but also relative strengths of muscle groups). On the other hand, your examples are efficient in the sense that the frequency of opportunity could be higher. Even broader, we could argue even moments of stillness is a response to prior actions, so teaching beginners how to create the state of kuzushi in uke is really complicated.
With that in mind, the mindset I like to take, and that I would teach, is that each throw has some ideal body postures that makes a technique applicable. And teach the mechanics of the technique. Finally, some efficient ways to achieve making uke take the posture.
For example, osotogari has a fairly obvious requirement for uke: he needs to be back over his heel. The mechanics of osoto gari isn't so hard either - it's a see saw (or a mechanical couple as CK puts it). But what is really hard is making uke take this posture, since it's easily avoided.
In other throws, the difficulty might arise from different sections, like required position or mechanical fundamentals. I'm just using osoto as an example.
So in teaching osoto, after a student has mastered the mechanics, I would show how to make kuzushi. It is unrealistic to expect to capitalize on a split second mistake by uke. Most people fail to do osoto because of this. They almost treat it like a bad footsweep. They try to rush into it when they see it but are too late.
My favorite method of getting osoto is to lead uke forward with his opposite foot, then apply. It has a lot more components to it, so I'd rather not type it all up. But I can say that I would never have developed it all without understanding the mechanics. A kuzushi diagram wouldn't have those components. It is way more complicated. You've got to understand several steps ahead to know how to create the moment.
What I was trying to get at before is that many judo players are reactionary. Whereas I believe that real kuzushi is when you are proactive, and can manipulate uke into taking positions you anticipate. That is the only way you can up your accuracy, except I guess unless you an old master like Mifune who has an answer for everything... I wished I was that good, but I found out I wasn't.