I hear they are great for asking how merge sort works during interviews for a CRUD application.

I've used one precisely once in my career to date and that was only to make modifications to something someone else had already done on there.

There's a huge one to the right of me which hasn't changed once in the 6 weeks I've been here - although since it says "NEXT SPRINT: [project X]" and Project X still hasn't really started, I guess it's always correct...

I do use it from time to time, especially when trying to get a common understanding about a fairly complex problem with other devs.