Learning skills not linear?
I feel like characters do not necessarily learn skills at a particular percent of Knowledge in the bestiary. For instance, I just learned Bash from Black Bear at 2 bears / 10%, before I even finished the tutorial quest that seemed to expect me to kill at least 5 which I presume is 25%. I seem to recall it taking 5+ bears on the previous character.
It seems more like killing a creature in the Bestiary has a chance to teach you a skill based on your Knowledge % - the higher it is, the more likely you'll learn the skill on the next kill. Probably if the Bestiary entry is 100%, that means you'll always learn on the next kill (or on the kill that gets you to 100%.)
My current character has 10 INT, the previous had 6. It's entirely possible that INT influences Knowledge percent gains and/or the rate of learning skills.