There are different levels of courses with different kinds of assignments. Depending on its content, you can only open the next lesson when you complete the current one. If you are good and have firm understanding of a certain topic, then it might take just few mins to an hour to complete a lesson, and open the next one. We do have some courses, which open lesson section wise. The example of a section in a lesson are: basic, advanced, aesthetic, technical, presentation, etc. So, if you complete the basic section, you may open all the lessons for advanced, if and only if the assignments of all the lessons of a section are on same criteria or need same elements. Keep in mind that teaching assistant need to go though your assignments which do take some time. So please be patient for grading.
When you start a diploma, we always suggest to start at least two (2) courses at a time. So you can do them simultaneously, and you don’t need to wait that long for your quiz to be graded.
By the way, this is already explained in our FAQs – https://www.lightandcomposition.com/faqs/university-scholarship-and-course-related-questions/#only_able_to_open_one_or_first_few_lessons