I went to a good university with a decent CS program, and I'd definitely say I learned a lot more on the job than I did in school. I didn't always have any mentors to speak of but I did have at least a couple who were good.
On the other hand, we certainly learned more after graduation (or something is wrong, right?). When I was in the AI course, the CS department was all about symbolic reasoning I didn't even know that Hinton was in the same department. I think what matters is the core training stayed with me and helped me learn new stuff year after year.