Oftentimes they're not even rigorous. At least in the math setting, many professors excuse their student's lack of comprehension on complex material when it's r

Oftentimes they're not even rigorous. At least in the math setting, many professors excuse their student's lack of comprehension on complex material when it's really bad teaching. Some attempts at explaining proofs are laughable and although their conclusions may be correct, because the covered theorems were proven by those much smarter than them, the steps taken to get there rarely follow the tight logical sequencing needed by those learning the material.