Your question seems to be along the lines of "Is it possible to speed up the process of seeing that the separate, egoic self is an illusion?"
I think it is. In fact, Rupert Spira and others talk about "The Direct Path" for doing exactly this.
Why do you ask?
Basically, it's one of those "what is possible?" questions.
One thing I've noticed with various different spiritual teachers is that it seems like a personality type match is highly beneficial - for example, Rupert never did much for me, whereas people like Ram Dass, Alan Watts, Terence McKenna, Jiddu Krishnamurti I can listen to for hours. I wonder if there's something that could be done about this as well.
To speed up a process, I usually try to identify the rate-limiting step (the constraint.)
I would guess that one of the factors that affects the time required to see through the illusion of a separate, egoic self, is "How badly do you want a much better existence than the one you've been living?"
Invalidating a low-level assumption of the kind we are discussing has to trigger a lot of re-evaluation by a person. In other words, it really turns everything on its head. I think people are often very smart, in a sub-conscious way, and they can see where self-inquiry might lead, and they say to themselves, in essence, "Screw that. Too scary!"
On the other hand, if you're really suffering, you'll probably pay a high price to escape it.