That's actually the main limitation of Vatians.
They have only one version of the future written in their mind and can only sense if things are going according to it or not.
Revere actually was trying to make sure things happened according to what Materia saw for the future, as he wanted to control as many variables as possible while changing only one at a time.
And that could be how Materia finally dies. Something changes so that her ability is no longer relevant and then she can't keep up her tricks so she eventually makes a mistake.



