Not a lot actually -- maybe 30 minutes a day on average, if that? And some of that I was listening to songs I'd pinned to my device. I did have it turned up to the highest quality, though... Still, the data usage seems excessive.



One thing that might be relevant is that I did have the "cache during playback" feature turned on, so maybe it was downloading entire songs even when I skipped in the first few seconds. (Not really loving Google's "I'm feeling lucky" algorithm -- Pandora it is not.)

I've disabled the cache during streaming option and will be monitoring my daily usage more closely once my billing cycle rolls over.