There are horror stories in New York around parents asking, "Why no social studies for Junior this year?" and being told, "Social Studies is only covered on the high stakes exam next year, so that's not my problem."

Standardized testing implies you really have to nail the test design, and be vigilant that people aren't working just to the metric, and aren't cheating. (Freakonomics has a chapter on how they caught cheaters in Chicago. Apparently they caught them in other cities too but didn't have the courage to fire them elsewhere.)