This is the part of the system that no one can agree on the explanation. When I line up on a visual, my perception gives me the unique eye address of the given shot. This is not something I need to think about, perception does the work for me. This can be realized at the table by anyone giving it an honest try. This is why "objective" comes into play because at a conscious level it is just edge to A. If you want to call perception "unconscious adjustment" I don't really care. What I do know is that it is consistent and repeatable, enough to result in high ball pocketing accuracy. I'm using ball centers edges and quarters to find shot lines using unique identifiable repeatable perceptions.
Try this. Setup shots #1 and shots #5 from perception video. Pick one and line up right CB edge to A(or B if that is easier). Just the single line. From that eye position take note where the CCB line crosses the rail underneath you. Now move to the other shot and repeat. What you should find is the CCB offsets differ in offset a little bit, maybe by an inch (I have not measured but I have noted them recently.) if you are not familiar with CTE, keep going between the two shots, really focus on the edge to A and CCB line. See if you can find consistency at a location and mark it on the rail with a hole reinforcer.
Take note both lines are perceptions for your own vision center. Use both eyes and find exactly edge to A (or B) and then CCB coming straight back to the rail. Try all 5 shots, see that the offsets are progressive.