The question of about how many pre 1950 do you find in a box? I buy about ten rolls at a time and find about ten pre 1950. I save them just to have something for my efforts so I feel like I accomplished something.
It depends on your motive for collecting. If you are collecting with the intention of making money, you won't make any money on these nickels. If you're like me and you just like them, then you should collect them. Since the classic Jefferson nickel is out of production then these old Jeffersons are going to slowly disappear from circulation. I'll continue to stick every one I find back (Unlike most collectors, I save the 1960s for whatever reason.)