I think it's only worthwhile if you can collect more "precious" metals. The guys collecting steel or even "dirty" metal (I think that's the term - it's good metal like copper, brass, etc but it's mixed, still has insulation on it, and so on) etc, based on the vehicles they drive, they aren't taking in lucrative money. I used to save up copper from plumbing, scrap wire, and so on and even a small box of it would get me $20. Another time, we replaced a dishwasher and I disassembled it, down to some copper fittings as well as the "stainless steel" tub. I got $6....

Since then, any scrap metal goes to the curb on the day before trash pick-up. I do separate it for the scrappers who come around every Sunday afternoon/evening (Monday is track pick-up).
I used to work at a large chemical pump company and our pumps were made out of many different types of stainless steel, hastelloy, even titanium and when the shop guys in our R&D group took bins to the scrap yard, the workers would almost fight over getting our scrap to sort. Made me think those guys got commission based on what they sorted. Another time, one of the workers in the foundry stole a 5-gallon bucket of nickel slugs. He took them to a nearby scrap yard and his mistake was, he took it to the same scrap yard that "bought" our manufacturing scrap. Wanting to stay on good terms with us, they collected the guy's info (name, driver's license #, etc) and stalled him. They called their contact at the foundry, told them what was going on and who it was, and were told "We're on the way. Call the police to have us meet them there too."