Does school testing work?

I understand the need to make some kind of general assessment to see how schools are doing. We do need to measure how students are learning and progressing, but how much testing do we need to do though? I think we spend way too much time testing and not enough time teaching. We make to much of the test, and not enough about learning. It used to take a week to give the standardized test. Now it takes over a month and the time is increasing every year. In the long run, testing does nothing to help students learn. Maybe we should do less and less of it and spend more time teaching kids to read, write, and think?

What do you think?