This is still how (many) CS problem sets were done at Harvard circa 2008, except we had whiteboards instead of chalkboards.
(There was no technical reason that problem sets were done in the lab - I think it was just less depressing to be coding at 3 a.m. when you knew you weren't alone).
Here at Berkeley we have the same thing. For example, I had a computer-oriented discrete math course where the professor decided a fun time to have homework due would be 8:00 AM. Naturally, you could pop by the lab next to the turn-in box at obscene times in the morning and see a bunch of people working.
One benefit of this is that sometimes great discussions about completely random--although usually technical--subjects emerge as everybody is procrastinating. It really makes even the most annoying homework assignment bearable.
(There was no technical reason that problem sets were done in the lab - I think it was just less depressing to be coding at 3 a.m. when you knew you weren't alone).