Has a heavily requested feature ever completely flopped after you built it?

Spent a whole month building a custom export tool because it was the #1 request on our feedback board.

Once it launched, barely 4% of the people who voted for it actually used it more than once. turns out they didn't really need the feature they just wanted to know the app had the option.

How do you test if users actually need a feature before wasting weeks building it?