How much time passes on the Material plane while Astral Projecting?
From reading various wikis I have the impression that the Astral plane is timeless — time doesn't exist there. I imagine this would mean that to an Astral traveller, all points in time on the Material plane would be accessible somehow. That would effectively allow both infinitely-long “time outs” by hiding in the Astral plane, and allow them to go back to any point in time in their own past.
But maybe I'm missing something or misunderstanding what I've gleaned in my browsing. So, how much time passes when and where? Does it matter if someone is on the Astral Plane or some other? How much time exactly — what's the ratio?