I am nearing the end of the skill tree, and have noticed that there is a penalty when you know a bunch of skills. For every new skill i finish, extra time is added on to the rest. The amount of time is not insignificant, for really touch skills it can add days onto the time needed.
I still havent done the better learning skills, and was considering them, when I realized that if I learned it I would probably lose more in penalty than I would gain. That got me wondering, assuming your trying to learn all skills, at what point does better learning stop being worthwhile at all?