I personally agree with some posters above me's comments... I think we have destined outcomes but we have free will to how long it takes us and when we get there, and we may need to learn lessons beforehand.
I also think that spirit keep some things from us on purpose, otherwise we wouldn't go through with certain experiences/lessons. For example; a reader could see you reconciling with an ex partner but what they won't be shown is you could be with that person for a couple months, 5, 10 years and then split. Things happen on purpose, you need to get involved with that person again to learn lessons and because of unfinished business, but if a psychic got given "you'll reconcile but he is going to cheat on you one day and you'll both split", you may go "ugghhh I can't be arsed for that hassle" and won't stick around for him, and you miss out on the lessons and experience with that ex you could have reconciled with and should have. So I think spirit personally do leave things out or aren't shown the full picture themselves because you need to live your life too, along with things being destined.