Depends on the work. I do code all day, but the codebase I work on is massive, fairly old (although some parts have been updated) and everyone in the office has their own area of knowledge. What the code does is also complex enough that it requires specific domain knowledge to code properly (I suppose "expert system" is the correct term), so you can't just throw general computer science at every problem. In that type of environment collaboration among developers is vital, I often leave in the evening not because there's nothing to do but because almost everyone else is gone and I've exhausted the bounds of my knowledge. At that point I can bang my head against a problem for 5 hours or ask the local expert the next morning and get my answer in 5 minutes.

But yeah if I was just churning out CRUD apps then I'd probably be more productive on my own.