@Jetah It sounds like there are multiple ways to get a skill. Each skill has a total of 6 tasks attached to it, but you only need to choose which 2 are right for you in order to study the skill for yourself.
Also, @Althalus , I'm not sure I quite understand your suggestion as being more immersive. That sounds more immersion breaking. If you want there to be difficulty, and not all players have the same experience completing tasks, it should be based on their attributes. For example, when I take a driver's test, I have to complete certain tasks to pass and get a license, allowing me to use the skill Legal Driving. When I complete those tasks, the teacher does not roll a D10 and have me parallel park that many times, or take a freeway ramp that many times. He has a structured test to gauge our qualification.
Also, the animals matter. If I'm learning how to sprint faster, hunting elk or gazelle would reasonably teach me that. Not hunting fish or birds. It sounds like the knowledge system is already heading in the right direction.
That all being said, such predictability does indeed lend itself to guides, just as much as it lends itself to a player asking an experienced player in game "How do I learn this, Elder?" and the experienced player responding "Ah, gather close and lend me your time, and I shall tell you how I mastered the ways of said creature." This is more immersive to me, and guides aren't going to do as much harm as randomizing the value of effort would.