Specialize or not?

Currently it's hobby with the intent of getting to the stage of an income supplement later on.
My space is limited, so big bulky ferrous stuff isn't in the cards right now, but dense heavy stuff is.
Working full time makes time an issue.
My plan is to learn, do "general" scrapping within my limits, develop a good relationship with the various yards all with the intention of eventually moving it into a side business as an income supplement either just prior to, or when I retire.
I may never see maximum dollar return, but as long as I get some money flow then I think it will be fine.
Now that being said, if by some fluke chance it does better than I expect, then I'll look at things a little closer and see what the outcome might bring.
Going slowly I think will be beneficial because it gives me time to learn and also determine the extent to which I'm willing to take things as I move towards my golden years.