> Most major research uni profs are obliged to teach 2-3 courses per semester.
IME, that's a heavy courseload. At the university where I work (not as faculty), it's closer to 1 course per semester on average. Maybe 2 occasionally, but that leaves very little time for research.
Your profile says you're a mechanical engineer. At research universities, 1 course per semester is typical in engineering departments. That's definitely not the case across all departments.
I'm also an ME, but I have a masters degree in Marine Science. The professors in my graduate program usually only taught one class a semester, some only one a year. From my experience it very much depends on the university. Some schools are much more focuses on teaching and others on research.
IME, that's a heavy courseload. At the university where I work (not as faculty), it's closer to 1 course per semester on average. Maybe 2 occasionally, but that leaves very little time for research.