For those with young kids, spend 15 minutes a day during K1 and K2 reading bedtime stories together with the kids. By P1, they should be able to read by themselves simple books. If you are able to do this, keeping up in school should not be too difficult. The maths needs basic reading skills. Mother tongue is up to your own prioritisation.
If you missed that, you will need at least one hour every weekday for 3-6 months to supervise their homework. This is where parents due to panic or laziness, outsource the homework supervision to tuition. A lot depends on the student care centre, there are some more responsible ones that will actively supervise the homework.
The current situation is due to the marketing efforts of the American style experiential learning of the premium kindergartens, the extremely lax childcare centres which together had started to cut the enrolment rates at PAP community foundation kindergartens. To boost enrolment, individual PCF centres started modifying their curriculum to be more interactive and less tough. If you are looking for someone to blame, look in the mirror. It's because of previous parents voting with their wallets that led to this.
Why do you think MOE started kindergartens and sponsoring non PCF kindergartens. MOE used to just issue guidelines of learning outcomes. But because sinkies parents started to skew the incentives. MOE bobian have to step in to regulate. The problem should be eliminated in 3-6 years. If you want to ensure that your child is properly educated by play, enrol in the MOE kindergartens.