Let me interrupt myself to weigh in on having students read aloud in class. I don't make anyone read aloud in my classroom in front of the group. I take volunteers. Well, I take some of them. I try not to be harsh, but there are some students who would go on and on during the whole class period without modulating their voice a single time. Although this makes a great teachable moment since the class is unlikely to ever forget what the word "monotonous" means, it tortures your captive audience needlessly and nothing is added to their understanding of the piece.
Especially with struggling readers, I do not ask them to do any "cold readings" unless I am sure that they will be successful. Yes, round robin reading does not happen in my room. I may pre-assign paragraphs or passages and give readers a chance to preview and practice. I need students to focus on the meaning of the words, not their dramatic performance in class.
A few years ago, I was so thrilled when my target class read scene after scene of "The Diary of Anne Frank" aloud. They read it like they knew what had happened, was happening and would happen. Wow!
Even so, much to my disappointment, they could not even answer basic comprehension questions on the scenes they had just finished. All they were able to do was to keep up and tread water. I didn't build in enough time for them to pre-read or re-read. They needed an opportunity to think quietly about what was taking place on the page.
On the other hand, advanced readers will power through this particular play quickly and understand most of it. Your not-so-careful readers will miss some of the finer nuances that happen when you think about the stage directions in conjuntion with the lines, but they will get the big ideas.
Before you ask students to read aloud, make sure that it will be to the benefit of the class and that the student is prepared enough to be successful.
If you would like another opinion regarding round robin reading, here's Ms. Laura Robb's take on the subject, http://blogs.scholastic.com/laurarobb/2010/03/please-bid-farewell-to-round-robin-reading.html