Nice, congrats on the ld and the excellent dream control!

I'm not quite sure if I understand your question, do you mean to ask if lucid dreaming interefers with learning? I don't think you need to dream about a specific topic for the information to sink in. Just be sure not to be sleep deprived, especially before exams. As long as you are able to get enough NREMs and REMs you should be ok, no matter what the dream contents. By the way, at the more advanced stages of lucid dreaming - when you get lucid very often there might be some beneifts for learning due enhanced brain capacity, especially by employing Gamma brainwaves responsible for greater concentration. Meditation sessions also help.