Oneman is spot on, in that it depends. Personally, I've only got a standard CRT TV, so I can get away with 5-6 episodes per standard disc. I'm sure on a large HD TV they'd look awful, but for me they work fine. You could various combinations to see what suits you. But then again, discs are so cheap these days you may as well use the minimum episodes per disc if you're that bothered about quality.