> Big productions tend to mix assuming you'll play on speakers (where it's fine to have something playing on just one channel/speaker, since both your ears will hear it), but when it mixes down to stereo and you listen on headphones, it's soooo common for them to pan something 100% to one channel when the source is supposed to be on that side.

I find this genuinely baffling; I lived for nearly a decade as a bachelor in a basement apartment where I had a big TV setup, but out of respect for my upstairs landlord listened to nearly everything on wireless stereo headphones, and I can’t recall ever experiencing this.