I had half an hour to spare and I let my 6-year olds read and read to their heart's content. We have a big basket of books in the class and whenever they have time to spare, they can take a book or two to read. Of course, the books are changed constantly to avoid boredom.
Honestly, not all children love the books or can read very well, but once they see many of their friends doing so, they will join in the reading. Some chose to read in pairs, sharing and telling the story to each other, some preferred to read on his/her own. Most are confident to read aloud, and usually enjoy a book more after I've read or told them the story.