Since the astral plane is just the collective unconscious, I doubt it would be much use. Just like channeling- you never know who's talking.
Don't get me wrong, I write down everything I get (or I used to) and about one in four things is stuff that is happening, but the rest is something someone dreamed up, or is dreaming up at the time. That's why I don't believe in prophecy. Too hard to tell 'facts' from 'mind noise'.