I'm not beta NF, but I'm pretty good at seeing how various situations with people will unfold. People's predictability is on a spectrum and the more predictable someone is the faster you learn them and their rules.

You know how to approach somebody and what to say to them to produce the correct result, for example. You know how to smooth over a bad situation you got yourself in.

It's more difficult to utilize predictions when you are not trying to control someone, though. For me this manifests with being able to use my idea of someone to inform myself of what their opinion might be without having to talk to them.

Whenever someone is really predictable I'll do this mid-conversation and piss them off if I'm particularly impatient with it that day.