Good readers' eyes take in more than 1 word at a time and each group of words forms a unit of meaning. Let's study the following examples (Move the pointing hand to the example you want to see):
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Example 1: just 1 word at a time + no meaningful group of words, so not effective
Example 2: more than 1 word at a time + no meaningful group of words, so not effective, either
Example 3: more than 1 word at a time + 4 meaningful groups of words, so effective
Example 4: more than 1 word at a time + 3 meaningful groups of words, so the most effective