And yet, not only did most of us millions of students spend a lot of time preparing for the exams, I have not heard of anyone who disagrees that preparation for these exams, for answering these unpredicted questions. was not central to our success in answering them.

And yet if I wanted to know the position of a student on a particular issue of philosophy I would rather read a 1 week homework assignment than a answer that's written in 2 hours without access to outside sources.

I also would think that even in an exam most student would spent a minute about exactly what argument they want to make before starting to write the argument.

We also don't have debates for the purpose that politicians spend a lot of time preparing for debates. If debate preparation is central for success in debates that's not a feature but a bug.

We want that the positions that politicans argue during the debate informs the viewer of the sort of policy that the politician wants to put into place should he be elected.

If asked for a policy on issue XY towards which the politician hasn't put much attention a good politician shouldn't make up an idea of a policy on the spot. If forced to do so, the politicians is likely to make promises about policy that he won't hold.

We might win the debate by making up a policy on the spot that sounds nice to the audience but that's not what you want to encourage.