Have read this thread with interest.
I think it is totally irresponsible not to do some sort of 'formal', tying-up of lose ends over the summer holidays with school-age children. In addition to all the fun-based learning you are all doing, naturally of course.
You should look upon it as supporting your child's teacher and preparing them for September.
For example, DS2 has finished Reception with a few 'niggles' over how to form some capital letters - he forgets how to write some of them - and likewise with some numerals. It is not a big deal for us to practise a little writing some mornings, just for 10/15 minutes, so that he will return in September quite confident in how to write all upper cases. I think there is a basic requirement of me to sort this out, frankly. He also is a great fidgeter and practising the art of sitting still, keeping his letters on the line and concentrating for a short period will, I am sure, do nothing but good.
We are talking a small amount, but something fairly regular here. And yes, in a 'formal' way, if you want to describe it so.
DS1, who will be going into Yr4 in Sept, has lots of academic issues to work on, and the summer hols are a prime opportunity for this. The time away from school is equal to a term. He spends much longer on his work, is keen to do it and knows that he needs to. But we are still talking about a bit of work in the morning, with afternoons off, and 3 days in the week with no 'formal' work, just reading practise.
We also have a week-long family holiday coming up, and have planned plenty of playdates, trips out, treats, swimming, riding, you name it ... My aim is to return to school in September two well-rested boys who have had loads of great experiences, and who are a bit more confident in some academic areas than they were in July.
I am stunned that people would take an 'anti' stance.
And I am a teacher.