Recently my mind has turned to the subject of plots. I'm current running a 4e campaign with a long overall plot and backstory. All the adventures are connected to the main plot, and the PCs are picking up clues as they go along and are slowly piecing things together.
So far things are going well, but my plot is a deep one. Red herrings and traitors and grey allegiances abound, and I wonder if the whole is a bit too complicated. It's been work for me, as DM, keeping everything straight as far as what the various bad guys are doing, so I naturally worry about the players. Can they figure it all out in the end? I should note that this particular group in composed of long-time roleplayers and more than one RPG industry professional, so I think they are up to the challenge (as do they). But how deep is too deep?
Deep background often makes fun reading for the DM, but is it really needed if the players often never penetrate beyond that first layer? I recall reading Dungeon back in the day and skipping past adventures that had a page and a half of background. Those always got looked at later—I wanted to get into the room descriptions and "good stuff" quickly. I simply didn't have the patience for all that led-in material. As a player, I often have a "Where's the beef?" style of play too.
I'd say my initial anti-deep-background attitude came from the fact that I learned the game in the 1e days, but I doubt that accounts for all of it. And not all early adventures were simple, with regard to background material. Remember the Temple of Elemental Evil? Good luck to any players that could piece together that infernal tapestry of demonic alliances pulling the Temple strings!
Recently I've scaled back my campaign from an end goal of 20th level to 10th level, so this also has me reconsidering the overall plot complexity. (I won't talk about that plot here, not yet anyway, lest my players be clued in.) I'm not planning any big changes, but a refinement is the order of the day because we'll have a good 20 fewer play sessions to work with. That's a lot less NPCs to meet! (My initial plan would have been great back in the days before most of my players were parents! Now, not so much. I tend to dream big before reality sets in.)
I'm not sure what the perfect balance of backstory to encounters is; I guess, as with most things, it comes down to what you and your players want from the experience. I was careful to repeatedly ask my players about their feelings toward an overall plot versus isolated adventures, so I recommend talking to your players too. In the meantime, I'll see how it goes for me and release actual campaign examples here when possible.