Another reason why I recommend breaking up a complex skill challenge into stages and running each stage as a less complex skill challenge.Here's another topic for discussion - number of failures.
The errata has placed skill challenge failures at 3, always. Which gets rather ugly when you consider skill challenges with 12 (!) success requirements.
I personally think that's too few a safety net of failures.
Not to distract from your point, which is good. But, I want to ask you some specifics about this.My point is that waiting for the players to ask the right people the right series of questions in order to unlock this mystery might take several hours of roleplaying. But by using successes from skill checks as an "excuse" to give them hints then you guide them along the path to where the main part of the adventure is. And of course you can throw them a few red herrings along the way to account for their failures as well. It seems to be a really useful narrative tool to me.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.