> In general, being good at academics require you to think carefully not quickly.
Yes, but to go even further: timed tests often test, in part, your ability to handwrite quickly rather than slowly. There is great variation in handwriting speed — I saw it as a student and as a professor — and in classrooms, we should no more be testing students for handwriting speed than we should be testing them on athletic ability.
In general, timed tests that involve a lot of handwriting are appalling. We use them because they make classroom management easier, not because they are justifiable pedagogy.
I can not think of a single test I have ever taken where I could be limited by handwriting speed. Most of the time on tests is spent thinking, not writing.
This is true about other things like reading speed as well. It still doesn't mean that time limits are useless. These are skills you can develop up to a reasonable level through practice if they're lacking, not something fixed like height. And if it takes you 12 hours to get through a 2 hour test because of these factors it's a sign that you're not going to be a very effective employee/researcher. Being able to read/write with some haste is not unrelated to job/academic performance.