However, I want to address that "Even native speakers can’t do much with a word they can say, but don’t know how to read or write." should be the personal conclusion derived from the learning approach of native Chinese children(include Taiwan).
But however, this is exactly opposite to what it is. Even though it often depends on the bility of each person, but logically, a native speakers is able to twist Chinese words more easily with more varieties than many of other languages, say, English.

Though the total number of characters is sitll unknown, the amount of Chinese characters used in PC is 13,053, standard Kang Xi dinctionary has 49,188, and about 75,000 characters identified for certain input method, so just like by having more types of flower will provide a garden with more choice to decorate, it's the same things with Chinese, more compoments the better, and they all share the relativity to each other.

To acquire a new language successfuly, finding a better method is a good approach for overall imprvement, however, many people have forgotten that the purpose of changing method is to "Mentally shift our focuses for the better efficiency". So in conclusion, instead of searching for the best method(which doesn't exist), I myself personally usually observe which focuses and in what situation are the most efficient ways to serve a cerntain purpose of learning such as writing or listening for the overall improvement.

I wonder which method is better, learning it all at once. Or to learn the speaking then reading and writing afterwards.