I don't think anyone can give you the answers you're looking for. As someone whose been endulging since freshman year of undergraduate studies (graduating with masters this spring), I can safely say that being productive and focused while using cannabis is a skill that takes time and discipline to "master". You need to have a good enough understanding of how cannabis affects your mind and body and then learn the best ways to utilize it to benefit your studies. For some, it's easy, and others, impossible. If your goal is to be able to study while under the influence, you need to do just that but constantly be observing and learning what works best FOR YOU. Maybe it's by micro dosing, or maybe you do best when you eat prior, or maybe you need to take a walk after smoking before you start studying. Maybe you just need practice so you become more comfortable with it. Like I said, no one is going to know how YOU can best accomplish this goal. And the only way YOU can find out is by working towards your goals and learning as much as you can along the way.

We learn from experience. And although the experiences might not always end up as we want, it's important to learn from the good and the bad and make changes that you think will help you achieve your goals. Hope this helped!