No. But it's good if you can, and usually means you'll be a more well rounded artist.
Generally speaking, larger studios tend to have more specialization where you're more likely to work with dedicated concept artists. Smaller studios, you might be expected to do more design / concept work yourself.
Sometimes. I work on indie projects that have tiny teams, so often I have to provide character turn-around sketches / environment concepts / paint-overs if they don't have a dedicated concept artist. It's a useful skill to have.
Replies
Generally speaking, larger studios tend to have more specialization where you're more likely to work with dedicated concept artists. Smaller studios, you might be expected to do more design / concept work yourself.