Efficiency above is in the context of me reading, not in the context of a nation or culture's literacy. Here are two more tangible examples: consider a traffic

Efficiency above is in the context of me reading, not in the context of a nation or culture's literacy. Here are two more tangible examples: consider a traffic light that has no colors, but flashes "stop" and "go" in text. The analogous "efficient" in my comment is the colored light, in which you don't think about the phonology of the words but understand its meaning. Other example: a digital vs. an analog clock. This doesn't apply to everyone, but it is plausible that you can tell "oh, it's late!" by looking at the shape of the analog clock, whereas in the digital clock you'd have to parse the numbers. "Efficient" would be the analog clock. Again, this example is suspect; it doesn't apply to myself (I read digital much faster). But in any case I'm not using "efficiency" to describe the writing system; I'm using it to describe a mechanism in reading comprehension.