Daniel Edwards (read: @headguruteacher) was absolutely correct when he argued that too often we misjudge the impact of our work relative to the effort we have put in. He is right to focus on curriculum, timetabling, performance management and assessment 'overkill'; these all offer plenty of inefficiency and I fully agree that you really can have too much data.  

This last is quite a statement and I know that in the past I have been known as a full on data fiend. It was, however, appropriate to its' context. I had started at a school in Special Measures and data in English was all but non-existent. What there was lacked rigour and too many pupils were able to slip through the net. This situation demanded a focused approach to gathering, interpreting and using data; the investment in time into this collation of data was appropriate, because the department was now able to monitor, support and improve the learning of pupils.