<p>Some classes do legitimately require 3 hours/credit every week, but it’s usually just a few. But for a technical 3-credit class, 5 hours of class+study time is usually the right number. Add anywhere from 50-100% to that number if you’re not quick with the material, a category that includes most people. Labs are more work than their worth in credit hours, as a general rule.
Most students shouldn’t have more than 30 hours of out-of-class work except on the weeks of many deadlines and exams (these do happen though).</p>