I don't have a problem with it at an earlier age in an effort to improve reading ability. Of course, if a teacher want to limit a child from expanding their reading ability, there is no point. This year when homeschooling my DD8, we made her read longer chapter books. Initially, she took forever to read her one chapter for the day. She complained like crazy. After a few weeks, she was reading in 1/10 of the time from when we started. After a couple months, she started to actually like reading.