> ...how to do that without homework?

Tests. Many of my university courses only graded on tests. They strongly encouraged you to do the homework to better understand the material, but didn't consider homework completion when calculating your grade.

Consider that universities are educating adults who are -often- paying to be there. If we assume competent course design and instruction, if an adult chooses to not work on the material until they understand it, then the only person they're harming is themselves... which -as an adult- is a thing that they're usually fully entitled to do.

I liked the classes I had with a "reverse" format: the "homework" was done in-class, checked for correctness but not part of the grade, and the lecture was a recording watched at home.