School put DS on this after Christmas in yr1. It was sold to me as they were doing it to speed him along and because they knew he had a supportive family who would put the time in too support this. There was very little other information forth coming.
End reception, we'd also started a phonics based program at home Dancing bears and it had become clear he was struggling to hear all the sounds in words and hadn't therefore really got phonics.
The extra reading ended up being 20 min every school evening and at weekend on top of normal 10 minutes reading and on top of the 10 minutes phonics stuff and other stuff - and I had other DC needing time - it rapidly got to a burden.
We had lots of arguing because as normal I refused to allow picture looking for clues and guessing - and tried to insist of decoding words which wasn't what he was being told to do.
DS is now a fantastic reader - he passed the end of yr phonics test with really high score. I'm sure this is put down to his participation in the reading recover program - he did do extra reading because of it but it's not the whole story.
He'll read a book at school, memorise it and then read it back to me at home so it seems as though he's doing well..
My eldest did this too and school could never see an issue.
It has caught up more and more as she gets older with her spelling an big problem area, reading is now much slower than average - it shows more and more. She started reception knowing all her jolly phonics sounds - yet their mixed approach which they said was phonics encouraged this behavior. She since had extra phonics lessons at school and I've started various phonic based reading and spelling stuff with her but it playing catch up and fill in the gaps and she has bad habits that she clings to.
I wish I'd done a solid based phonics program like dancing bears from start with her because she didn't get that good grounding.