IIRC when I was in college, the rule of thumb is that most classes require about 40 hours of outside work, 50 if there are labs. Harder classes require more.
Used to take six to seven coursed per semester three semesters a year. Got out a year early. Studied and worked hard those years. Little debt.
For the hard sciences (I was a chemistry major) the rule of thumb was three hours outside of class for every hour in class. For a full class load, that works out to about 40 - 50 hours of "homework" per week.
I found that to be just about right.
I went year-round carrying a full-load of classes, starting with summer school a week after high school graduation.
I was the first person from my high school class to graduate college early, in only three years.
And I worked three part-time jobs and played in two sports. Always busy and starving.
I got out with a business degree and no student loan debt.
Life was good back then.
I took 21 hours/sem and went summers to get out in 3 years. I hardly ever studied. Finals were an excuse to have week long card games.