Oh dear god, I'm in that Drawing for Animation class that you're in (lol).
I'm not in the animation department, I'm actually in Illustration at CCA, but I can attest to the dropout rate. I'm in the second half of my junior year and we haven't lost half of our class or anything (our class is an anomaly that only started with 18 people, which means we're a particularly small graduating class and we don't get a choice over who our Illustration teachers are for any semester; we're down to 13 now.) but as we move towards thesis we're losing people. We started this term with three people who didn't come back or took breaks (but they just haven't actually come back).
Some left because of the rigor, and some left because it wasn't giving them what they needed.
I guess I can't speak for the animation department but the Illustration department's workload was like going through hell. Last semester I was getting 8 hours of sleep A WEEK. I don't think it gets lighter, I think you just learn how to manage your time and figure out your limits.