Yeah, once you have a few higher level slave set up to get you net positive gold and food, it's very easy to farm learning point by shift your slaves into library. That's one of the reason I prefer the old system other than the immersion problem. It's too easy to farm learning point after you climbing the initial curve where you only have one low level slave, and even that curve is more of a gentle hill rather than a steep mountain once you know what you are doing.
Then again, the mental stats doesn't affect jobs that much aside from high courage for hunting. So it's more of a personal nitpick rather than a deal breaker.
