Getting him to read the reader book thing is hard. He isn't interested AT ALL in doing that. So this is why he rushes over it & doesn't really read the pages. He even says he read it at school so why read it again?
I really don't think they are an effective way of teaching him to read. Yes ok it may be what all kids do, memorising the words that go with that page etc but I think it would be much more effective to have him making sentences with words that we can change every day. So say he still has a set selection of words each week but then rather having a simple story he will just remember, having word cards we can make into things. KWIM?
Repetition is actually really important in early reading development. I know it can get a bit frustrating, but you can make it fun as well. Maybe play games, get him to find a specific word on the page, find a word that rhymes with .... (fill in the blank), find as many words that have a specific letter in them. Take turns reading with him, get him to make up his own story to go along with the pictures. (Sorry, my brain's running in slow motion tonight , I can come up with more suggestions tomorrow if you want?)