For me it's where I'm developing a task to do stream processing and classify the data by an arbitrary subset of the data and don't want to model the entire stru

For me it's where I'm developing a task to do stream processing and classify the data by an arbitrary subset of the data and don't want to model the entire structure to avoid losing/changing the original data structure. I'm sure there's better ways to do this, but that's an example I'll throw in.