The case study method, popularised by Harvard Business School has been adopted by almost all the top MBA/PGDM programs in the world. For your bachelors degree (engineering, commerce, science, etc), the teaching was almost fully dependent on the lecture method. In contrast, best management colleges spend less than half of the time on lectures.
In short, case studies are a miniature version of a business situation used in MBA/PGDM programs to facilitate learning.
The percentage of case study dependency ranges from 20% to 80% in the top business schools in the world. It gets varying degrees of support from the other methods of teaching – lectures, group assignments, experiential learning (internships, real world assignments would fall in this category).
Learn About case studies: https://www.gibs.edu.in/gibs-finishing-school/