It all depends on how much you find versus how much you think your time is. For the first 4 or 5 months this year I would find roughly $40 to $50 worth of metal in under two hours so it was worth it to me. Competition has increased so much here in Orlando over the last few months that I don't even bother any more. I simply refuse to drive around for two hours to make $20.
Also keep in mind that you need to break things down to make the most money. Keep all clipped electrical cords in a pile, electric motors in another pile, clean copper in another, and so on. Good luck