I agree if DS is keen and not worried by the work then carry on and don't panic, ask him how he feels.
However having been through the system with 2 children ( moderate amounts of practice papers and no tutor - one 'passed' one didn't) they are both doing exceptionally well at their different schools with fabulous GCSE results ( proud mum!) Colleagues ni a deprived area with poor schools also have children celebrating great results this week.
I guess what I'm saying is, I got very stressed by 'the system' in Trafford and felt I had failed 2nd child by not pushing more,but have realised ( too late for my nerves!) that success in GCSE's is down to aptitude and hard work whichever secondary school they are in not what extra work they did at 10.
Good luck to your DS whatever the outcome he sounds like he will do well wherever he goes.