I know very few university students with significant work commitments.
In the US, the stereotypical college student is not also holding down any kind of job. Maybe 5-7 hours of "work study" (light work running the reference desk at the library or working in the dining hall).
Frankly, I doubt the majority could do learn a lot and also work a significant number of job hours.
At a community college, it would be very different - most students also holding down jobs, I would guess. At a flagship state university, I would be very suprised.
Evidence in [1]... about 30% of full time students are working 20+ hours/week. Also apparently I was wrong about the low hours being typical; less than 10% are working but < 10 hours/week.