[prewett]

Heisig's method is for kanji, which have different pronunciation depending on which word they are in, since Japan imported the meaning but not always the pronunciation. Note that the book is called "A Complete Course in How Not to Forget the Kanji", not "How to Read". All he's doing is endowing the character with an image that conveys a commonly used meaning and how it is written, so that you can remember it. Actually reading or pronouncing a text is out of scope.

If you're learning hanzi you can take advantage of the pronunciation hints. Plus the fact that modern hanzi generally have only one pronunciation per [traditional] character, and only one syllable per, too. The characters made so much more sense learning Chinese.