I have just read a number of discussions on Singapore’s education system and the Chinese curriculum there. Singapore manages to pack a lot of learning for their students and has a world class educational system, as far as standardized testing is concerned. As best as I gather, Chinese is taught as a stand-alone class, at most one period a day during school, as the rest of the school instruction are conducted in English.
In any case, I looked up some reading samples from Singapore. Here is Singapore website published by the Ministry of Education in Singapore. Click on a 高級華語 textbooks for the first semester of sixth grade. The passages look very reasonable to me, for 6 years of daily one-period instructions with established CLE in the country. I think my 9 year old should be able to read these in traditional characters or very close to reading them proficiently.
I then looked up China’s textbooks for first semester of sixth grade. Here is one link what I found : 6th grade textbook.
It appears, to me at least, that China’s Chinese reading level is higher than that of Singapore’s. That’s not surprising given, I presume, almost all classes are conducted in Mandarin Chinese in China.
So, once again, more exposure / learning = higher level. Simple as that.