Well, one of the oddities I saw with the 4e structure was the obvious problem of challenges involving Knowledge skills: People who don't have the right Knowledge skill (or even the ones who do), but try to think of an answer and come up empty? Those count as failures.
Or, to quote Superchicken: "If you think, don't drive, and if you drive, don't think!"
When paying attention to the challenge and even trying to think of a solution can cause the entire party's efforts to fail, there's areal problem with the mechanic.
I ran a classic BDF (Big Dumb Fighter) in our 4e campaign. With an 8 Int and no Knowledge skills, his best contribution to such Skill challenges was to ignore them and walk away, while trying not to go to far or get lost.
<tangent>I wanted, strictly as a joke, to have him take the Ritual Magic feat sometime around or after 10th level. With the IQ of a fruit fly and no Religious training, his first feat of Ritual Magic would be to raise the dead. The rituals you could use were based on your level, not how long you'd had the feat, and the system didn't care if you'd come into the feat with Arcane training or Divine, once you had it you could cast either type of ritual. Hey, if nothing else, they system was good for laughs.

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