Depending on the particulars of the exams as well as personal preferences, there are several ways to prioritize and plan study time for midterm exams.
How to achieve this priority
Nonetheless, the "ABC" method is one strategy that is frequently suggested:
A-Priority: High Importance/High Difficulty: Take on the most significant or difficult issues first. These could be the tests for courses with challenging material or ones that have a big impact on your final grade.
B-Priority: Moderate Difficulty/Moderate Importance - Next, focus on subjects that are either moderately difficult or moderately significant. You may need to dedicate a significant amount of time to these courses, but not as much as to the high-priority ones.
C-Priority: Low Importance/Low Difficulty - Lastly, set aside time for subjects that are less important or relatively easier for you. This does not mean that you should ignore them; rather, it recognizes that you can afford to spend less time on them without sacrificing your overall performance.
The number of alternate schedules will depend on how adaptable your study routine can be and the constraints you have (e.g., other commitments, work schedule, personal preferences). Let's consider a simplified scenario;
You have several combinations of time slots for each subject if you have five tests (A, B, C, D, and E) and you want to make a study plan where you set up particular time blocks for each subject. You have 3 * 3 * 3 * 3 * 3 = 243 ways to arrange your study time if you have, say, three time slots in a day.