I’ve been a student for over 20 years now…10 years at University for my secular life and going on 12 years at Seminary for a graduate degree. One thing I’ve learned about myself is that I do better studying every day rather than taking entire days off. Now that I’m only taking one class a term, I do have that luxury if I chose…but I’d rather spend a half-hour or so reviewing on Sunday than let it all “leak out”.

After all, I’m only carrying three credits a term now as an adult student, having a full-time profession and family to take into account. I do remember the years of 18-21 credits per term though.
If you’re a full-time student, you have an obligation to do the best you can to do the best academically that you are capable of doing. At the same time, you have and obligation to the Lord, especially on his day, and to yourself in terms of taking in some relaxation time.
As long as you have your priorities straight…Lord first…studying on Sundays is not problematic.
Tips from a long time student:
Do not procrastinate. Even if you do a light review, review all of your classes every day. Let’s say you have 13 credits; 2-four credit classes, a three credit class, and a two credit class.
Ideally, you’d spend 2/13ths of your study time on the 2 credit class. I’ve always used 3 hours of study time per hour of class time per week as a starting guidline, adjusting for what classes I found to be more difficult and which classes I found to be easier than others. So, 2 credits x 3 hours per week per credit hour = 6 hours per week, or roughly 45 minutes a day for that class.
Now, someone else might get by with 2 hours study per credit hour (those that are brighter than I am

) Same thing applies. If one class is really easy, shift the study time alloted for that class to one that is more difficult, and be prepared to ramp up the overall study time the week before exams and especially during finals week.
If you procrastinate, you will eventually get behind. If you get behind, you’ll likely get stressed. If you get stressed, your learning efficiency goes way down, and if your learning efficiency goes way down, you’ll have to put in that much more time studying to catch up again.
As well, mastering procrastination will serve you well out there in life. We all do it to some extent, but in general more successful people, whatever they do, get more done with less stress if they minimize procrastination.