In reply to colin godbold.
good question - there's always a need to balance cost versus benefit for everything we do - resources are always constrained, but we use data to prioritise our effort. Note to self: must get portfolio team to get blogging about their wall!
Similarly, we always to design our services such that we know when and why we're not meeting users' needs (see https://www.gov.uk/service-manual/measurement/performanceframework.html ) and can then fix any problems we spot quickly and cheaply.
Data trumps intuition, both for spotting improvements needed, and prioritising them.
