In our school, the vast majority of assessments are only given to determine whether your child is at grade level. These tests are designed to demonstrate NCLB compliance. They don't look at whether your kid is beyond grade level.
I see this type of testing as imposing a ceiling on high ability kids instead of a floor. No one looks at what the kid really can do, i.e. read two, three or four years above grade level, and thus they have no idea whether your kid actually progresses during the school year. The gifted kids can be completely stagnant but for the purposes of NCLB, they're good.