OP, I agree with you - if it's for your ds's benefit then all well and good. If it's to cover shoddy and/or incompetent teaching then let them whistle.
If at a later date, he really has a problem, there's always Kumon.
For those who find 3pm a late finish, I never finished primary school before 3.30pm, had homework every night from the age of 7, learned tables up to 12x12 at the age of 7 etc etc.
In my last year at primary school I learned separate subjects of arithmetic, algebra (simultaneous equation and solving quadratics) and geometry - which I always hated. Thank goodness I did modern maths from 11 -16. I also had French and Latin, history and geography and art. Every Friday morning after break without fail we had a Latin grammar paper with the major distraction of the headmaster's golden retriever licking my knee, and then my nose, when I didn't pay her any attention. When she got too stroppy, he used to send her back to her corner by the ink bottles.....
I didn't chose any of this, and in addition to 2-weekly positions in class for points for my house (or team) and written exams twice a year (Christmas and Summer), just took it in my stride. At the same time, on a sunny afternoon, he cancelled lessons and took us out either over the beach, or at high tide, over the hills to run off steam among bracken and heather - with the dog in tow, of course.
The school results - long before SATS - were extremely good. The head knew how to motivate and teach children more than any teacher I had before or since. Shame that teachers like that are so rare.
For those in Germany, the post-war system of education there was based on the current (at the time) British system of primary followed by either grammar school or secondary modern school with the possibility to transfer to grammar school at 12, 13 etc.
DH did that - they carried knives at his primary school, and I refused a grammar school place in the local convent, preferring to go to another school where we rather resembled St Trinian's on a bad day - complete with lacrosse sticks and indecently short skirts. The convent with white gloves in summer, indoor shoes etc etc would have killed either me or the nuns.