I think what Tanarii is getting at is in 3/.5 knowledge checks had a clause that you could not retry them unless you gained an additional rank in the skill. Essentially, if you rolled a 1, that was your knowledge for that topic at least in the short term. It made it possible that more generally knowledgeable characters could still be beaten on specific topics sometimes, coupled with approximately 80 bazillion knowledge(subskills) it could make for a very diverse team of scholars.