I really liked this image of the inverted U from Peter Morville's Ambient Findability so I decided to make my own version:
InformationAndDecisionMaking

I'm a strong proponent of data-driven practice, particularly for classroom- and student-level progress monitoring of essential learning outcomes. But, as Morville notes, there are diminishing (and even negligible) returns if one goes too far. We have to know when to say when.