At least that's what's expected. What usually ended up happening for me was blowing off 30-40 hours of classes a week, doing some 10-20 hours of studying (including homework and such), and having a near full-time job. Then followed by some 15 hours of studying per day during exams.
But I never graduated. So that probably wasn't the best strategy. Although I did get a bunch of solid work experience in my field.
That sounds like an extremely unusual balance of classes vs studying. An 'average' class-load is something like 12-18 credit-hours. That's supposed to mean 12-18 hours of in-class instruction per week. I'm quite curious how you ended up taking 30-40 hours of in-class instruction, and if that was normal compared to your peers.
I was told in orientation (in 2003) to expect 2-3 hours of outside work per classroom hour, and my experience matched that. If these students are facing the same expectations that I faced, then they're getting a 1:1 ratio of classroom:outside hours, which is underworking by a significant factor.
Which means my original estimate was wrong, but coupled with holes in schedules, potentially taking extra classes in a semester (I think the max I ever did was 7) you easily ended up spending 30-40 hours a week at school if you were going to all your classes.
That's how it was at my run-of-the-mill European public University. But I did always get the impression studying in the US was much easier.
In the olden days computer science programming was done in labs because few people had the precise combination of machine / OS / compiler / IDE to match the class requirements, things are a little better now...
Most people can learn only so much withing a day and can focus only for so long. I would guess that 6.8 hours can be quite close to the point where your focus run out and you are bound to waste the additional time by staring on book (as opposed to learn from it).
The rhetoric for as long as I've been alive (I'm college-aged) has been "get a degree, get a degree" and as it turns out getting a degree isn't very hard. We need to either make it harder or somehow change the rhetoric to "learn something."