After reading your long comment, I agreed with you said about different type of methods.
So in my P4 pupils, they can understand the use of units and numbers. In fact, for P4 pupils, I have talked to their parents there may be a need to talk to their Maths teacher during the Meeting the Parents session.
Fortunately, none of them need to. This is because the pupils can perform in their problem solving.
We are always aware that different kid learn in different ways.
Those can use the school method will always perform well, because they know the tricks. I believe the tutors here are experts in this, and your children will always top in class.
Those who half half will always get borderline marks, because no matter how hard they try, the problem always got something to trick them. Their parent will always ask them to “work hard”. In fact both parents and kid do not know how?
Those who do not know how to use the school method will just sit down and relax, because they know that no matter what they do, they are always wrong.
We should be more concerned on the second and third group of pupils. Maths are very flexible. There are many ways to solve them, not just one school method.
So long that a kid can perform more than 10 questions, there should not be any reason to stop him to use a new skill.