I've seen in a few places that asteroids in belts return after 2 hours??? Does this mean I can just mine somewhere come back later that day and mine it again? Just trying to get into mining? Any other tips?
I'm not sure of the regeneration time, but yes, they eventually do regenerate.
However, mining in asteroid belts is a bit of a waste of time. (A shame - I wish there was a reason to actually go into them.)
What you want is to go into a planet's Ring and laser-mine there but in
that case, good luck ever finding the exact rocks you'd found before. (OK, there
was Egg and Son Of Egg, but they were special circumstances.)
It doesn't really help to wait for regen - just fly in a more-or-less straight line, popping prospectors all over the place and zap the good ones. You'll fill your hold much faster that way.
