Just me, but if it took 320 hours to do one level of high school math (say, Algebra 1), I'd give your student TWO credits, one each for Algebra 1a and Algebra 1b. That brings the credits to approximately 160 hours each, and closer in line to the lighter World Religions credit of 120 hours. And if all the other credits are more at 160-180 hours, then I'd consider the possibility of awarding partial credit (say, 0.66 or 0.75 credit) for the World Religions, rather than a full credit, for consistency.
Another possible explanation for having a course run overly high on hours is if the student was doing dual enrollment or AP or highly rigorous Honors course -- then be sure to indicate that in the name of the course ("Honors Algebra 1", or "Calculus, with AP test", or "MAT189: Statistics") on the transcript, and that helps make it clear why it took so many more hours.
As long as you're shooting roughly for consistency -- like the way Merry described of 150-180 hours for academic subjects but 120 hours for electives -- or have a solid reason for the wide variance in hours -- like Honors courses -- then you're fine.
If you hours are all over the place, then you might want to re-evaluate how you are setting up the requirements for each course, and see if you can slightly tweak them to bring them slightly closer to consistency. And if that's not possible, then you can explain in your course descriptions why course X took so many hours, and course Y took far fewer hours.
Edited by Lori D., 14 October 2017 - 07:17 PM.