So you would do the entire cardigan in the round and then steek it?
Well, some of us aren't very comfortable with steeks yet, which is why I do three separate balls of yarn when I get to the arm shaping divide. I did this with a sweater not too long ago, and it was quite easy to keep all the balls/yarn untangled--in fact, much more doable (at this point in my knitting life) than steeking. And I liked this a lot better than doing one side at a time, too.
It was just a recommendation: so take it or leave it!