They do. It’s called quitting for awhile or taking a break or as the British have wisely done: taking a gap year.
Physical accidents happen suddenly and are pretty much unforseeable or unpreventable.
Burnout has a more gradual arc and can be ameliorated with some common sense measures such as those suggested.
If one is totally exhausted and thoroughly fed up at the end of the semester and a few days recovery after intense test taking doesn’t do the trick it may be rather foolish to sign up for yet another semester rather than taking a break.
Just because one is burned out by so much nose to the grindstone studying doesn’t mean they are unfit or so disabled that they can’t work at a fairly mentally undemanding type of job for six months to a year. (Or if rich enough, take a vacation in the Bahamas or volunteer somewhere as a change of pace.)
Common sense. Insurers don’t generally make a habit of betting against it :)