Studying high is probably not the greatest idea. Obviously, what you are studying is also an important factor. If you need to write a creative essay that requires you to think outside of the box, the smoking beforehand might help. However, if its numbers that need crunching, smoking weed might interfere with your ability do your job. At the end of the day, its all up to your personal preference, and your understanding of how smoking affects you. Take the time to figure out whether studying high works for you, before trying to study for your big final blazed out of your mind.