Implication from phonology for teaching reading and teaching a second language!

It is difficult in most of the time to apply the structural analysis during reading. It is true that the knowledge of the meaning of roots, suffixes and prefixes help to understand or at least to assume the meaning of the new word. But it is not always appropriate to assume the meaning of the word by dividing a word into the parts of the different morphemes as it is difficult to define suffix. As text says it is helpful during vocabulary test to pick the right synonym out of a list of four answers. I remembered while giving GRE, one of the most valuable tactics was to assume the meaning of the word by parting it into different morphemes and try to correlate the meaning of the words according to the text but as per my personal experience I even did not find it very worthy as the list have similar meaning and it is really hard to find out the exact meaning of the word. It is not possible to apply during the reading of connected text. Thus in my view, it is not very worthy to understand or know the meaning of the word through dividing the words into the parts.