I would bet that in most fields, the majority of university graduates never have to do work at the level they did in school again, and certainly not in their first job. The only place I could have done things as "advanced" as what I was doing in my last year or so would be if I went on to get a Phd and did research. Likewise, my father made a great living as an engineer, but the kinds of things he did in general on a day to day basis were not as complex as the things he had to do to get an engineering degree. Another example would be doctors who become GP's (or anything other than surgeons or researchers, ie, the vast majority) -- the kind of work they do day to day is much easier than what they had to do to get a medical degree.
How well you do in school doesn't hint at all for how well you do at work, in school you are just doing it to get out of there, work you are doing it to get paid and sustain your living so you would work harder at a job than you did in school.