Instead it might be better if those who want their children to repeat the year keep them down a year
I don’t think we are able to choose that option. I would have done that for ds2 in reception if so. Schools don’t allow you to decide that. They have full classes of 30 coming up so no space for people to stay behind.
Your first scenario puts your child at a disadvantage, because his/her classmates will have covered work that s/he will miss.
The second (quite apart from being forced on the child rather than a choice by its parents) puts your child in exactly the same position as their classmates. None of them will have studied new learning and left classmates behind.
That doesn’t seem to be the case at dc school. They are being set a full days work in exactly the same way they would have learned if at school. New topics. New maths concepts. New phonics and English etc.
I think it’s not going to be the case that they are all behind to the same extent. There will be huge divides between those who had 1-1 tuition at home who were already quite able and those who were behind to start with and have not had any home schooling.
Some will have had parents working and lots of siblings to share little or no resources with and others will be only children with a Sahp.
I feel so sorry for teachers who already have to spread themselves over 30 children with varying abilities. This is going to make it like teaching 2 or 3 different year groups in the same class for some I expect. I imagine teachers are desperate to get back to it as it’s only going to be harder the longer they leave it and the further the kids separate.
Ds1 will now probably go to yr 3 unable to read and ds2 will go into yr 2 unable to read and count. :(