These things are definitely down to the professor. Both of my cases were great teachers. My Calc 3 class was probably the worst, the prof always showed up 20m late, but he pulled the most funding in the department, so he did whatever he wanted.

Grades are a way for teacher and student to check their learning, but teaching still needs to happen regardless of checkpoints. Some subjects require practice, like pre-proof writing in math and many other introductory to intermediate level courses. This is where homework comes in handy.

For my set theory class, the professor still assigned problems, he just never collected or graded them. For my Data Sci 2 seminar, it was only seven of us and we did several presentations and a papers.