So generally I would say that they learn where to stop (or never see the depths of the endless pit that is knowledge in the first place) with the help of a good

So generally I would say that they learn where to stop (or never see the depths of the endless pit that is knowledge in the first place) with the help of a good teacher or textbook. A textbook that tells you just what you need to know, and just enough of what's happening under the covers to let you think you understand, and solidify what you're learning