Consider this scenario: 2+ shows were simultaneously aired, and had some
crossover. (Example: Buffy and Angel.) It'd be helpful to be able to view the episodes of both shows together in a
single list, to be able to sort them by air date. But, I believe that to
currently do that, you'd have to manually add each episode to the list -
I can't see how one could add just the shows, and then expand them into
constituent episodes, when viewing the list.
It'd be really helpful if you could add, say, 2 shows into a single list, and then when viewing it, have the ability to instead view them at the episode level. Or, if that's not possible, to have the ability to add a show to a list - but then instead of adding the show as a single object, it'd add each episode of the show separately. The latter, I think, would be especially easy to implement.