An exception to piling on each other (if what I've seen is accurate) is the Night Gallery Complete set which has all single-disc hubs on each side of the "pages." It's 12 discs so I'm surprised they didn't streamline like this Invaders 12-disc set.
Thanks. So only one disc to juggle when picking out discs to watch, that's not so bad as some of the other complete releases. The Mary Tyler Moore set requires you to juggle 4 discs.
Looking for an informed response, not a guess. If I had to guess, I'd predict the discs overlap or are stacked, so in that situation, I'd get the separate releases.