There's less burnout in school because there's a goal. You put in effort, you get an A. You get enough A's you get a good job.
Some put in effort but don't get an A. That can cause burnout.
Some put in effort, get A's, but don't get the dream job. That's a massive source of burnout and depression.
It can stretch on further too. Some land the dream job but don't land the dream home. Another source of grief.
But for the most part, the grading system can also shield you from burnout because it feeds you the results you expect to get from the effort.