Context
An organisation had scoped a fairly large product around one flagship feature, based mostly on internal conviction rather than user evidence.
Assumption tested
Whether that flagship feature was actually the reason people would use the product, or just the reason it was easy to pitch internally.
What the data showed
In practice, users largely ignored the flagship feature and kept returning to a smaller, secondary workflow instead.
Result
The scope was reduced substantially around that smaller workflow. Some of that was uncomfortable for people who had already committed to the original plan, but the revised version was something people actually used.