how long does it take to get the rolls down on a banjo?

Answer 1

I know what you`re talking about, "forward roll", "reverse roll" "forward reverse alternating roll", "the hammer lick" they just go on and on. All I can say is practice makes perfect, if you wanna get good you have to play every day.
Good luck with that!!

Answer 2

It's not just getting the rolls down, but being able to separate your right hand movements from the left hand movements and do them both at the same time. If you use a single roll for the whole piece, it's easy, but alternating between rolls takes much more time and practice. Eventually, your focus will shift to the left hand and making correct chord positions. At this point, you should not even be thinking what the right hand is doing (assuming you are a right handed player). You'll get there!