I agree with what you said that some deja vu act as life markers and the idea of life being scripted in such a way that there is a set plan for everyone. Where I may differ is the idea we live the same life over until that set plan is completed. I had an occurrence many years ago that supports that idea. I had deja vu that was triggered by a song and then I got a glimpse of how things would be had I not met a particular person. To this day, if I listen to that song I still get a hint of the despair the glimpse showed.